You should go on to more advanced topics without being fluent in less advanced topics. You can always later go back to the exercises that stumped you. The typical student taking calculus without being fluent in adding fractions is a mistake, but that don't over-correct that mistake.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)
3. Open Threads should be posted in Discussion, and not Main.
4. Open Threads should start on Monday, and end on Sunday.