This is a great article, one I wished I read a long time ago after a lot of inefficient learning.

One thing I'm still keeping an eye out for is how to best learn when time is limited.

As I get older, free time is at a premium, with job/kids/life/etc. meaning that some days even 20m practice is a luxury. So I've always been curious how to make the most of that and unexpected slots of free time.

Should I just work on technical exercises/scales? Have a set of things written down to work on in case free time appears? Follow the advice in the article? Or accept that nothing worthwhile can be done in such short time and noodle around?