Obsessing Over Rear Delts

Most people spending lots of time and effort doing isolation exercises for the rear delts simply haven't built enough general shoulder & back muscle and strength to display any visual gains.

Therefore, they have no results to show for all this rear delt isolation work they're doing.

Get stronger on your presses, rows, &  pullups. Isolate the side delts because they'll grow more quickly – and have a bigger visual impact than rear delt stuff – alongside overhead pressing, rows, and pullups.

Worry about the rear delts once you've built some muscle. Even then, don't waste a ton of time & energy with rear delt isolations unless you've got crazy imbalances (which probably are a sign that your upper body pulling strength or technique is garbage) OR if you're planning to compete in bodybuilding.

The only semi-specific rear delt work that I do is my Indian club swinging – a sneaky awesome rear delt and rotator cuff exercise – and I do this during my warmups or as an active rest day, flowing type activity.

I don't have outrageous rear delt development. But, I don't compete in bodybuilding and I definitely still have room to improve my overhead pressing strength. 

Don't major in the minors.