Like almost everything in poker, the answer is, "It depends."
I have paid a coach to review some hand histories and give me some general feedback on my game, and it was very helpful. I have also paid for a series of training videos that I also found very helpful. But... I can't be sure that the money spent was actually recouped in winnings. Mainly because I'm a recreational player and just don't play the volume of games that a grinder might play. But I like to learn and understand how to improve my game. I picked coaches I trusted to really know what they are doing.
On the other hand, reviewing
hands with a poker buddy is also very valuable. It's good to talk
poker strategy with someone and get feedback. That's why we have hand history review sections in this forum (
Cash Game Hand Analysis and
Tournament Hand Analysis) and also lots of poker training videos and threads. If you haven't already, check out these two threads for lots of information:
CardsChat Learning Poker Thread Series Guide
CardsChat 30 Day Poker Training Course