Yadi

Over years I have studied several subjects in depth by taking online courses, I'm curious to know what do others do or recommend after finishing a course?

For example a course on machine learning, or rather a harder subject let's say Algebraic topology: where do you usually go to clarify topics within the subject that you're in doubt with?

After looking at the recent [Who is Hiring?](https://news.ycombinator.com/item?id=17902901), I was wondering if there is a recommended personal approach to applying for multiple positions during the same time.

It seems like a chaotic and counter-intuitive process to apply for 4-5 companies simultaneously, but most do recommend this approach. Got any tips?