About 6 months ago I had never had a lesson and I played golf on average about once every 3-6 months for the last 10 years. My average score was probably 110-120. Within the last 4-6 months I have probably played an average of one full round per week (always on Sat or Sun), usually warmed up for 45 minutes first, gone to the driving range 2x per week on lunch breaks, and taken 7 golf lessons from a pro. Recently I posted a personal best score of 86 and I average in the low to mid 90s now.
I don't know when the progress is supposed to level off but I'm happy about all of it so far. And that's with playing only weekends and getting some swings in at the range a couple times a week. I plan to continue this amount of practice and ultimately if I can average scores in the 80s whenever I play I'll be happy. I say that now anyway. I feel as if getting to a single digit handicap playing only once a week is do-able as long as you have a practice area you can take some swings mid-week on. Big difference between thinking it's do-able and actually doing it though