Learning gaps

To keep it short..

I got my CCNA back in Nov.. I’m now studying from my CCNA. There’s some knowledge gaps that I need refreshment on.

Long story short, as the studies progress within JTIL YT concepts. Is there non stop repetition on some of the earlier taught concepts that I can focus on just working through day by day? Or do I need to focus on them early so it makes sense later??

Example -

Class A,B,C, etc. IP addresses. Same goes with 802.1 concepts. Lastly, cidr notations and available network / host devices.

I can’t remember off the top of my head, I know I don’t have a cheat sheet available to me during the test but I expect on the job I’ll have a cheat sheet.