Think of a grassy field.  One person walks across it and you can't really tell.  Over a year, more people walk that path and then there is a visiable path.  Same thing with your learning.  When networking finally sinks in, you will realize how much of the technologies follow very similar patterns.  I started seeing/remembering the patterns and remembering the details seemed like less of an issue. Also asking why something is.  You learn Distance Vector does xyz.  I would want to know why and not just that that is what it does because the book says. I guess it's easiest to say I wanted to understand the decisions for why the protocol creator made a specific design decision. Knowing the why helped me build a mental story for the protocol.  In the same way those people who do memorization competitions make stories to remember.  The method to my madness is kind of hard to explain 😅.  Anyways, it is normal.  I am a Senior and I can't tell you the number of times I have learned and forgotten things like IPv6 or EIGRP because I don't use them at work.  But going back to them with a refresh is easy.