If you are struggling with your rotation, trying for positional will just make you worse because you will miss GCDs, hit the wrong button, etc. If you are progging, going for positionals in unknown fights will get you killed. It is literally the last thing you should be worried about. Your number of crits matter more than you hitting prositionals, so therefor even optimizing your stats is more important than positionals. Quite literally the last thing you should care about when it comes to playing your class and thus reserved for those trying to get the highest parse possible those are teh only people that should be caring so much about positionals as it actually plays a huge role in cranking out that last possible percent of dps.