For a couple of years now I have been taking lessons from NM Nolan Hendrickson off and on.
One of the things that we have been talking about lately is my poor opening preparation. I don't really know the openings I play too well, and it's showing in my games. I get bad positions out of the opening in most games. Even when I win the game I normally lose the opening.
So Nolan and I scheduled a two hour lesson to cover openings. Specifically I wanted to cover the White side of the Italian since that is one of my main openings as White these days.
So I get to his house one evening a few days ago with my Italian stuff in hand. We go sit down at the board and Nolan says "We're not working on openings, we're working on planning. I've been looking at some of your recent games and you are not planning at all." I say "I thought we were going to work on openings." Nolan says "This is a bigger problem, so this is what we're looking at."
Folks, this is exactly why you want a player who is much stronger than yourself to be your coach. If I was studying on my own I would have just worked on openings and not even realized that I have a more serious issue going on right now in my games.
The point of having a coach is that it's a shortcut. You don't have to take lessons every week for a coach to be effective. When Nolan is in town and not at college in St. Louis I average maybe one lesson every 4-6 weeks. Sometimes more, sometimes less. This works out to maybe 10 lessons over a period of about 21 months. Since I take two hours at a time this means that I have had roughly 20 hours of time with Nolan. But that time has saved me months of trial and error.
A coach will tell you where your weaknesses are. Where your strengths are. Where you should spend your time. Where you shouldn't.
The reason that this is such an advantage should be obvious. Let's say that you have a problem with planning (as I do) and it will take say 50 hours of methodical study about planning to fix the issue. A coach will point out the issue right away and you can spend your next 50 hours working on eliminating that weakness.
Otherwise, eventually you are likely to spend 50 hours on planning, but it might take you spending 500 hours on other things that aren't as important before 50 total hours have been spent on planning.
It's the same concept as making a grocery list when you go to the store. If you don't make a list you might still come home with what you need, but you might have to go back to the store five more times before you have everything. Going with a list on the other hand means that you'll come home with what you need on the first try.
So I highly recommend to anyone reading to take lessons.