Good advice. I have been playing a concertina for about 3 years, the first 2 1/2 on a 20 button that made my elbows ache. Last june I finally was able to afford a vintage 30 button (just love that C#). That was a great motivator. It has such a beautiful tone, I just love listening to it. I will try to hang on for the next 5 years and see what happens.
I can recommend that you only practice each tune briefly. As in 5 min. Then go back to marking papers, reading email, wasking dishes (or whatever) for 20 minutes. Seems that neurons in your brain take a while to respond, or soak up the practice and wire in the finger movements. If you pour all the water on a sponge at once, not much will be absorbed, but if you let it trickle a drop at a time, it will fill absorb more water.
Well that's my theory and I am sticking to it. By the way, it makes maring papers easier to take as well.
Bill McKim