After rambling I’ll answer the specific question.
I use my cycling notes in a couple ways. One is maintenance I have a general maintenance log and a running to do list. I collect specs, part numbers and “how to” instructions and notes.
For training I do a preseason goals plans and ideas note. At the end of each season I do a look back recap. Any good notes app makes it super easy to collect info of the web so if I see an article or post of interest I click and it’s saved. I write up or collect workout ideas for cycling and cross training etc.
When I was racing I’d do detailed post race reports I’d look back at those for example when going back to the same race year after year.
And, when summer comes, I can refer back to last year’s notes on how to prepare the perfect post ride cold brew coffee.