A few questions about fire rotation

This is regarding end-game PVE raiding specced as fire. When BIS, in what situations would refreshing LB instantly after it explodes be a dps loss rather than an increase? Let me give some examples.

1: I get a HS proc right as LB exploded and I have the t10 haste buff for 5 sec, do I bother refreshing LB at this point or only cast FB's until the buff is over? Since I'm BIS I can probably get 3 FB's off with the increased haste.
2: If the answer is to use FB, what if I keep proccing HS multiple times in a row for 10-20+ seconds, do I keep using only FB's until I have a short period where HS doesn't proc?
3: Is burning a GCD for LB during heroism/bloodlust still a dps increase?

Well to be honest there are some situations but in my opinion you should still refresh it.

1. Ok so the first situation is if you are trying to keep up your ignite debuff on. If you are able to do that for extended periods of time then ofc refreshing LB might compromise your ignite debuff making it drip from the boss.

2. If you are using a 100% crit build. I am aware that you probably arent using this, but i just wanna say that if you were using LB at all isnt a good option cause at 100% crit you will just be focused on dishing out fireballs and insta pyros keeping your ignite on untill the boss dies and you achieve 100-200k ticks.

3. This might sound stupid but I am saying it just in case. If your LB explodes during your cast, youre gonna wait out the cast, and in case you proc hot streak, youre still gonna refresh and then continue withe either another FB or consume HS proc.

4. At sindy flight phases, you should keep just dishing out as much as possible untill she gets cloce to your max range where youd reaply the LB so it ticks on during the tomb phase.

Now to answer your questions:

1. You still want to have LB on cause of the increased chance of extending your ignite debuff and getting mire HS procs.

2. This is just an adumption you will get so lucky with crits. It is still vetter to increase your odds by putting a LB on, not relying for pure luck to pop those HS procs.

3. Ofc it is, as stated on the answer to your first question: more ignite and more HS's = more dps. (Unless youre at 100% crit ofc :D)

In my personal opinion refreshing LB is also very usefull cause it makes you able to micro manage your positioning, giving you that little gcd window to move a bit and reposition without loosing dps. Sonetimes slowly shifting your position using the gcd windows can help out drastically while making your dps as high as possible. Also LB helps in refreshing your ignite debuff and getting more HS procs. I might have missed some points, but this is just some of the possible reasons from the top of my head atm. Good luck!