Originally Posted by Vaeryn

That's because the approach you describe is probably simulated here: Simulationcraft Results (there's MM Arcane and MM non Arcane which means Aimed is your focus dump in whole the fight; I wrote probably because I am not 100% sure about the assumptions used in that simulationcraft). In FD you can't exactly simulate the "arcane strategy" you're talking about. Of course you may mark the option: "Disable Arcane Shot while Careful Aim is active" and it won't be casted during CA phase, but that's it. It still will be casted during RF and Heroism so it will be casted during second wave of RFs or at the end of your heroism if then you're already outside CA or during second heroism if in settings you type in the length of the fight longer than 10 minutes. People suggest to use arcane outside CA and when unhasted because in simulationcraft the difference - as you can see - is not any big which favours it in the fights you're forced to move a bit - so in most of them.