I basicly just dps with all, and throw 4x lesser healing waves to top the tank when he gets too low. Chain heal to heal myself if I got the time. If the fight is very bursty, I have some extra macro's 'just in case' so two of my shamans heal the tank while my main and one other heal the mains target. But in all honesty, I rarely use those. And can manage everything with a single healing button jsut fine. Key is to target and retarget at the start of casts, so you don't loose targeting time. So when a tank needs a heal, and you just cast lb, immidiatly target tank and then heal, and when heal is casting, well, I got /targetlastenemy in my dps macro's so no problem there. my heal button if an enemy targeted also goes on the target of that target, so on bossfights who dont drop target (some do to use certain skills, some don't) I dont have to retarget at all, at most to heal myself.

Chain heal, unless blooslusted, is a slow cast time and you shouldn't use it when its too late. Healing tank always get priority, but just keep yourself up high, so when things go rough, you can last a lil longer, when you're getting aoe, heal the tank then chain heal yourself or just spamheal for a few secs while clickly rotating through targets which are lowest, this works well too in tight situations.

Anyhow, most if not all fights will have ways to avoid a lot of dps on you as a caster, so you should ofcourse prioritise on working on that.

I'd say having one resto will allow you do last longer in fights, more mana regen, prolly better gear, but at the same time you loose a lot of dps if you put one on inactive duty, and there are a lot of fights that also get easier with more dps. So it's fight dependand, but haing them all four on dps duty works for me, and until I find an encounter I need a solo healer for, I'll start considering adapting for those specific fights then. I have not encountered any yet however.