Could not agree more. If you don't commit to regular lessons, I think you are more likely to revert to your old habits because you don't trust what you should be working on. Whereas, if you know you have another lesson coming up, you trust that you can continue working on the technique and then go to the next lesson and get feedback to make sure you are making the changes correctly.
Personally, I
always
get worse right after a lesson until I groove the new move(s). Now that I have been working with the same pro for several years, I instantly trust what he tells me and I integrate it a lot faster. Now my problem is over-integrating. That is, even after I incorporate the change into my swing, I keep looking for that "awkward" feeling I had when I first started trying to make the change. For some reason, I feel like I'm reverting unless it continues to feel weird. Of course, that's not the case - I'm just learning to incorporate things faster and more efficiently now.
One step backward, two steps forward.