There is no such thing as an “off-season” when you want to be the best. There is pre-season, in-season, post-season, then prep-season.
Prep-season is when you reflect on what went well and what you need to improve on, then you get to work!
NOTE: This applies to coaches, too. The best coaches use the few weeks after the last match to read, reflect, and get ready for the next season.