Tom, apparently you played tennis on and off as a child and in your teens.
What I would like to know is when you resumed playing table tennis in your twenties, did your standard of play originally begin to lift? Was it practising your technique for your strokes, training sessions or getting coaching for yourself, or a combination of all of them?
When I started playing again in my twenties, I did start to improve, but any improvement was very slow. There was no structure to my practice and initially I had no coaching. Any small improvement was probably due to playing regularly. I turned up to the club every week and hit with different players.
However, when I started to analyse my strengths and many weaknesses more closely, then I did start to improve a little more. By identifying areas of my game which needed big improvement, I could structure my training more and focus on technique.
Then when I started to get some coaching, I was exposed to new ideas and techniques I had never even thought about. This sped up my improvement a little more.
Looking back I think any improvement I have had is a combination of regular play, focused practice and taking advice from other coaches and more experienced players.