Well, isolation work will actually bring up weak links in your chain. The day I started incorporating isolation work for my delts, tris, hamstrings, etc...what do you know...my bench, overhead press, squat, and deadlift all went up...and I added size everywhere.
If your primary goal is strength you can probably benefit from doing a few months of isolation/bodybuilding type routines every so often. If size is your goal then do it even more often. If bodybuilding is your goal then your question is dumb.
I love focusing on big compounds - the smaller muscles do grow.
I moved from a 5 day split routine, onto a 4 day (upper, lower, rest, upper, lower) split. Focusing on deadlifts, squats, weighted chins, flat bench, close grip bench, barbell curls, military press. That's all, no isolation work.
My calves got bigger, rear delts got bigger, as did my forearms.
Well. This is the bodybuilding forum therefore I assume your goal is bodybuilding therefore if your goal is bodybuilding then why are you asking if you should do Isolation work? That's like being a power-lifter and asking if you should incorporate bench, dead-lift and squats or if isolation exercises are enough....