...Let's start from there what exactly is DPS. DPS is damage per second. That means the game calculates every second your total damage done for 1 sec, the game does same for next 1 sec, and next and next, ... till end, and on base these intermediate calculations the game does your middle DPS what you see on your recount (if you see you recount in battle it refreshes recount's values every 1 sec)...
Well, you wrote a lot of text with a lot questions and on some questions you already done responses. I'm familiar what is dps and about this I wrote an etire paragraph (P2.5. DPS Trainer), where I calculated theoretically the damage of each elemental shaman spell and had introduced an example how those theoretical digits to project on practical values. Check that paragraph if you didn't. Talking about LB or CL rotation I didn't forgot about the LB and CL mechanics.
LB has flying time, but CL has instant hit. This is why I alway noticed that CL is good to perform some fast burst against low HP targets. Because due to CL mechanics we can do more output damage during short time (first 3-4 sec) compared to LB. It's very important vs targets which each second presence in the encounters can turn to raid wipe (for example, Blazing Skeletons at VDW). Such bursting rotation I already wrote in paragraph 2.1 Macros. The CL rotation burst is very effective during PVP also due to previously explained criteria. Moreove, fly time of LB can be encountered by Iceblock, Deterrence, Spell Reflection, Antimagic Shield and e.t.c. Finally, CL always should be caste after Lava for best output fast burst with minimal ooming, because after Lava will 100% crit we will recieve Clearcasting and 50% less mana cost on expensive CL mana cost.
You explaining DPS mechanics under theorycraft criteria as damage per second. Few posts below Bensten typed a right post about how Recount and Skada works - they fix the Entering Combat time and calculating all damage done during the combat time. The DPS is Damage Done divided on Combat Time (casting time). So, DPS after 20 sec is all damage done during this time divided on 20. Some practical kind of normalization. I performed many tests and can confirm that Recount and Skada aren't good tools to calculate burst DPS. Their digits are right after 10 sec of casting time, after some normalization.
Talking about Boss encounters the sustained DPS is better option than burst DPS. The LB doing better sustained DPS vs single Boss target as is shown below.
Also, you forgot about one basic and very important concept which determines the DPS of each class - the GCD. It's the main barrier for any DPS rotation which makes this game playable at the same time. Below is a graph example about LB DPS and how GCD limits it's value (posted in paragrah 2.5).
Example: Imagine you are in icc and you cast CL on single target and your overload procs and you hit 35k (20k from primary and 15k from overload). it will cost your recount 0s time to calculate this 35k damage.
Now imagine you are in icc in same situation but you were casted LB instead of CL and your overload procs and you hit 42k (24k from primary and 18k from overload). It will cost you and your recount to calculate this 42k damage around 0.5s time. How much more range you keep from your target this time between primary and secondary will be more.
So fast analysis: 35k for 0s always > 42k for 0.5s for this cycle of time DPS.
Even for this example i gave 4k damage done difference between CL and LB but it is less with same amount of spell power. Around 1-1,5k normal and 2-3k crit in ICC ..
Mate, I don't know where you got got those digits: CL hits for 24k and 18k for it's Overload. The 24k is a medium LAVA crit in ICC. Anyway, to explain this time line collisions I prepared two graphs based on SELF BUFF DAMAGE vs Heroic Training Dummies. One graph is based on spell rotation with CL, the other one - with full LB.
CL Rotation - a kind of PROACTIVE DPS
With green vertical lines are marked the GCD barrires during first 6 seconds. DPS1, DPS2, ... DPS5 are theorycraft DPS values during each second respectively. As wee can see, due to CL mechanics, between GCD1 and GCD2 we can push very high damage. The CL and it's Overload damage is done during the "second" second. Even during third second our damage can be high if next LB and FS DoT will crit. The output damage can be a way higher if CL will hit 3 targets,
but we are talking about single target DPS. After 6 seconds the
NORMALIZED DPS is 13.3k (as total damage of all spells divided on 6 sec). It's a case when LB crits are not so high as usually.
LB Rotation - a kind of BEHIND TIME DPS
Let's take a situation while our FS DoT, Lava and LB, during GCD2, GCD3, GCD4 GCD5, doing the same damage just to project and compare CL and LB more exactly. As previous CL has Overloading our first LB also has Overloading. So, due to it's fly time the LB Overload will land during third GCD. As a result the DPS2 will be a bit lower, but the DPS3 will be a way higher. After 6 seconds the normalized DPS will be around 14k. It's not even equal DPS, it's higher DPS. Talking about Boss encounters we are not interested when the highest damage will be done - during first second or during third second. We usually are interested what damage will be done after 10 minutes!
You said : "The CL is good to perform some fast AoE bursts and to synchronise your Lava Burst and LB with FS DoT sometimes."
Or this is total wrong in my opinion or just i can't understand what you mean. We talk here for some minimal part of the second like 0.1s or 0.2s where you never can calculate or synchronise in the encounter just because first you are not robot second it more depends from your haste raiting (what you never can sychronise too because no one can tell you what is ideal haste raiting for you even 5 haste raiting can broke this your synchronisation) and 3rd every moving from you will refute your theory - you don't know how much time you will need to move 1s or 2s or 1.9s or 4.3s or ... and when, just you will need to start all again. ..
Well, I'm not going to explain this in detail, because the abilty to synchronise your spell mostly depends by latency, lags, skills. For a person which plays elemental shaman as an ALT one hour per week or per two weeks the explanation will not help. This is a way how simple ele shaman's rotations become very hard. I can say only one thing.. During BL/Heroism, Elemental Mastery, Engineering Gloves, Potion of Gaste your casting time of spells will vary between 0.3 - 0.5 second. So, I personally have some sense based on my current haste (casting time) and distance from the Boss the next Lava will crit or not, if I'll "clip" FS DoT or not. Clipping FS DoT are bad for dps; you should synchronise your LB in the some way to cast new FS between 0.3-0.8 second after last DoT ticked. Clipping FS DoT you'll cut it's initial damage. If caste too late you miss one DoT source of DPS during 2-3 seconds. While you casting LB the target will be without FS DoT.
For example, let's say the FS DoT timer on BOSS is on 2 sec (it means that in 2 sec the FS DOT will perform it's last tick).
Based on my current haste rating and distance to Boss I know that I'll cast Lava in 1 sec and Lava will land in 0.7 sec - so it will crit. In other case I know that I'll cast Lava in 1.1 sec and Lava will land in 1 sec - so it has a 50%/50% chance to crit due to my 52% crit rating. It's good idea to wait Lava and fake it's priority and to cast next LB during 1,3 sec. The LB fly time is also 1.1sec. So, we have 0.7 sec to cast something different but not Lava (chance to do normal damage), not LB (because we will lost FS DoT on target for too long time), not FS (cause we will clip previous one). Sure CL is the option due to it's fast casting time 1-1.1 sec and chance to Overload and to Reduce Elemental Mastery CD and Frost Shock or Earth Shock are bad options (DEDICATED TO PLAYERS WHICH PREFER TO WASTE TALENTS POINTS FOR BOOMING ECHOES and /or SHAMANISTIC FOCUS). After CL will insta land we will cast insta FS just in 0.1-0.4 sec after last FS DoT will tick, based on latency, filled by Lava so the FS DoT will be set to 18 sec.