It always depends on the situation. You have to rethink your rotation when you have to move, when you have to burst, or under special circumstances like Ravana's increased damage taken during Liberation. If you know that there will be a period where you can turret, you might want to use SC to increase damage rather than saving it up for situations where B4 might fall off.

It also works fine if you have Ley Lines up, you can use your procs and still be in time for B4 even without SC.