I keep a spreadsheet.
And try to keep it updated.
Then have a chart of how many players at what position, and the upcoming FA's as well. Though that is not always updated throughout the season, as players come and go.
Also, I keep how many players at what position during the off season and TC.
I been doing it for years. One thing I regret thought, I don't always save it year to year. If I even wanted to go back and see what players were in TC. As I use the same file year to year most of the time.
I start back in the late 80's, writing it all down by hand. Then created computer files in the early 90's. Went to spreadsheets around 1997.
So when Jimmy came along. I had a lot of writing to do.