As you said, "As we all have limited time". Mostly I'm not learning anything without having a use case for it in mind before learning it.

When I have an idea to build something, I start researching which technologies exist to solve my problem. I spend quite a long time comparing different solutions. I check the activity for a technology on GitHub, StackOverflow, etc. I also check the google trends.

Once decided I which technology I want to use I start learning it and write a blog post about it at the same time.

Mostly I then don't complete my original idea but I end up with a dozens new ideas.