How to know if I’m making progress

There is so much to learn from this site. The concepts are deep and I believe it takes a long time to get into the “real work” of everything. I feel like I’ve only scratched the surface so far and I have decided to commit to pick something and go all in until I master it and then move onto the next. My question is – how will I know when I master something? I like things to be based on a time limit which is why I think I’ve only scratched the surface so far. I tell myself “this should only take XX amount of time”. And then I move onto the next thing. My other question is – how do I know if I’m just staying in one topic for too long and maybe not moving on because that topic is comfortable for me. It’s difficult when everything is up to me. I like someone being in front and telling me what to do. I don’t like leading the way. Even when it’s for myself.