I'm probaly the minority position here, but I think they are a waste of time, they are why we have guys spending tons of money are are very low ranked skill wise.
One hour? Is that a joke? I play with my son for 6 hours, we come back next day for 4, then 3 more, not all the time but you learn what works and what doesn't.
Maybe it's just I never had a teacher, just a old wood racquet and had to survive, and I did, and got better, and better, MY STYLE IS MY STYLE, I'm not doing someone elses style.
IMO, you should be taught, "Heh, hold it western, continental, or eastern", aside from that tennis is an extension of your mind unto a racquet to do a specific purpose, this can't be taught, practice and doing your own thing is what works.
I will tell you, teaching my son shows me how much I don't know about what I do, it's not rehearsed, it's not something taught, it's just me expressed, the glory of tennis
You are definately entitled to your opinion based on your personal experience. Mine is quite different, however.
First of all, I've ran across hundreds of players that believe as you do; almost everyone of them failed to reach their potential because when you are truly self taught you work on things that create immediate "success" and you try to build on that. Unfortunately, most methods, (unless you studied what truly successful players who do reach their potential do), that allow a player to meet some level of early success, (hitting the ball over the net, towards a target within a certain criteria of speed), seldom allow the player to progress to higher levels of skilled play. (Without making significant modifications in their swing.)
I've taught thousands of players who come to me from your exact mentality who complain that they not only can't get any better, (even as they know they have the ability to get better), but constantly are getting passed up by those players they used to beat. (IE: players who first developed a foundation of skills the typically don't feel all that comfortable or confident at the beginning.)
There are many exceptions...however, they are exactly that. I once had a coach in the southwest whose kid that was 'self-taught' by his dad who went out, like you, hit thousands of balls to his kid, (believing that they will excel, somehow, through attrition), and claimed he was a top player in that area. Well, I took that kid to So. California to play some of my kids who were taught through specific training: the outcome of one particular match:
6-1 for the Calif. kid
When the southwest kid asked "Is that your #1 player?" I calmly replied, "Yes, he is #1 Junior Varsity."
This "top" kid in the southwest wouldn't have even made my JV team, let alone my varsity.
This is also just one example...but, I honestly don't know a single truly top-ranked kid, college player, or even a top club player who didn't take lessons and/or study the game as I've described.
I would certainly not risk wasting a kids potential talent by "HOPING" he mastered the various stroke components through some osmosis or attrition of simply saying, "I am only going to do it MY way."
Ironically, those players who are taught correctly actually have a better chance at developing their OWN game because they don't possess poor form that MUST be compensated later. I've found in 35 years of teaching that students that are indeed 'self-taught' seldom have the means to do MORE with the ball...conversly, they often find themselves having to accomodate their unconventionality through limiting their strokes or game in some way.
But hey, they can claim "I'm doing it MY way!"