* If I spend these embers will I have enough to get my AoE started on this pack spawning in a bit?
* When do I conflag? Now when I'm on only 1 charge but may cap soon? Do I save Conflag for later when I need to move in conjunction with RoF, even if it's sub-optimal w/ no movement?
* Should I consume 3xBackdraft w/ Chaos Bolt?
* Do I Havoc a Chaos Bolt now or wait to try and get Shadowburns off adds a bit later?
* Do I reapply Immolate early or late to get crit buffs?
* How many targets do I hard-cast Immolate?
* If I RoF now will I get full benefit or will adds move?
* Should I RoF on one target?
* Should I be using Havoc glyph?
There's a ton of decisions that have no clear cut answer and can't really be effectively planned for. Obviously one could play without considering any of these things and only care about "whether or not to use an ember on low procs or wait ...", but that will only get you so far, and the hidden complexity shows itself in actual fights.