Most end game encounters you can get away with just spamming chain heal. Chain heal spamming will usually guarantee you ridiculously high hps on toravon.
The smart player will move away from using a rotation in healing and just use healing spells appropriate to the situation. This is where you have to triage healing waves versus lesser healing wave, while making sure ppl health aren't so low why you start casting the slow chain heal.
Shamans are the iconic "turret" healers. They excel in non movement fights, but become boring. However, for a real challenge, I recommend high movement fights like healing Halion 10hc in the shadow realm. It's amazingly fun, you must pick up instant ghost wolf form, use this to get into position quickly, and must do precise heals, because you have to move a lot.
If you are just doing pos fos rdf hc, it's Boring to heal, but come raids, it becomes interesting. Shaman healers are blessed with ridiculously powerful heals with short cast time due to tidal wave talents, but apart from riptide an earth shield or popping a 2 minute cd, they have no healing options if they need to move.