WieWaldi I had seen this video a while back, but I just watched it again and my main take from it is the advice to apply the general rule of "i plus 1" when choosing a new piece. So, instead of overloading the brain with too many new things at once, you aim to play something that includes no more than one new technique or concept. As Sophia pointed out upthread, this is quite similar to how the Alfred method books work, so that learners are never bombarded with pieces which are too much of a stretch. However, most method books only go to early intermediate level, so this issue of choosing the right pieces is going to occur regularly for us "self taught" pianists, unless we find a teacher to guide us. Maybe one day I'll do that. On my allotment site there is a music professor on the next plot to mine, and he mentioned that there is a piano teacher on the site too... maybe I'll meet them one day and have a chat with them.