Now it is time to answer to Mx Fox and their advice.
RFox Figure out the measure into workable sized chunks [...] Don't repeat this more than two or three times at any one time and ideally clear out the working memory with another piece between each repeat. [...] If you're adding a second session five or six hours later repeat the first attempt. [...] do this for a week (five days) [...] I would drop the passage for a week at this stage.
I did this with four measures, RH only, with four chords. Five days of practice, five days of rest, and these last two days I have had three repeats twice a day again.
I am sorry to say, but it doesn't work for me. Three repeats per session, especially three repeats broken by another piece, is just too little to make a lasting impression. Yes, first attempt on day 2, I needed less thinking time than first attempt on day 1, and first attempt on day 3 was faster than first attempt on day 2 but since then, thinking time has not improved. First attempt on day 12 (five days practising, five days break, second day since break) was only marginally better than first attempt on day 3.
I compare my memory with strength training. If you’re want to build muscle, there is a minimum amount of work required for any real progress to happen. Muscles only grow when they’re challenged enough to need repair and adaptation. This means you need to lift weights that are heavy enough and do enough repetitions to properly stress the muscles. The weight also needs to feel challenging by the end of each set for it to count.
Here’s the thing: if you don’t reach that minimum, almost nothing will happen. You won’t build new muscle, and the little work you do might just maintain what you already have. It’s not about doing "some" work; it’s about hitting that threshold where your body is forced to adapt. If you’re not doing enough, you’re just spinning your wheels without getting anywhere.
Memory feels the same way for me. Repeating four chords three times in the morning and three times in the evening, just does not make enough of an impact on my memory. Nothing happens. When learning something new, I need to put in enough practice in the first days for anything to stick at all.