Early in the season I will go for a quick 30-min check-up, just to make sure that my fundamentals are correct as I am working out the rust on the range getting into the swing of things.

During the season, I won't go back unless I start having a problem that I need to address, like lower-than-normal ball flight, or if I am starting to over-draw my irons.  This year, it was a lack of distance with my driver mid-season that I wanted to address.  One good session got me dialed right back in.  The year before, I was pulling too many short putts, and my pro had me change my ball position, and corrected it in ten minutes.

If, in your position, you are looking to take things to another level, plan on getting a three-pack of lessons, spread out over about 6 weeks.  This will give you time to work on the things your instructor has you working on, and allows for continued growth, as you spend time on the range and on the course in between sessions. 

Also, most of the time your guy will give you a good discount on a 3-pack, especially if you pay upfront.  You might do the first session on full swing, the second on short game shots like pitches and chips, and the last session on putting.  Or, it might be that you split your lessons into half full-swing and half around the greens, so that you are working on all aspects at the same time. 

Not enough - hopefully more in the new year!

My friends laugh at me, but I go once a month to my guy. And he laughs at me, and we just hit a few balls, and talk golf. Best $60/45 minutes I spend all month.

I think it is all about how much you want to improve... my optioning too many lessons will overload your brain with information, and too much can be damaging. Why not trial the lessons, book one work on what you have been taught and then a month later book another, if that works then great, if you feel that the gap is too long then when you book the third you could book for three weeks. I tend to book every month through the summer as I spend time playing and working on my game, but maybe less in the winter as I try to focus more on what I have learned throughout the summer, but if I need a refresher then lessons are always available. trial it and see how you get on :)

I visit my pro almost all two weeks to improve further on my game

I have never had instruction. If I were starting over, I would definitely start with instruction. One of the things I enjoy most about golf is trying to figure out swing flaws and how to improve. I currently have a 4 handicap and will often get near scratch in the summer. It has taking me much longer this way but I can typically correct things very quickly during a round. Also, I'm competitive but I try to keep the game in perspective by having fun and realizing I'll never make a living playing the game.

On a lighter note, every time I go to the practice range, there is always that one guy there that acts like everyone's instructor!

More seriously, I have been seeing my golf coach-instructor about 6 times per year, with most of the sessions being in the winter months as I tend to practice more in the "off season". This allows me to work on important concepts with my coach, including things such as my physical fitness program.

As I get older, it becomes harder and harder to keep the strength that I had as a young athlete and I become more prone to injury -- which detracts from my ability to play.

I guess it is what you are trying to achieve out of the game. I am 62 and never had one. In my prime i was a 4HC, now during the season a 10. If i was starting out again, id probably do some lessons. But i agree with what the person stated, you can have to many and get confused as heck. I would space them out and go to the range a lot. Thats where you can work your own bugs out. you know how you stand now in your game, and if you do, the hardest part is finding the right instructor. Good luck....