Try this in pre-season:
-Start on 30th of june (in Holland for example), make it as long as possible.
-General team training: Tactical on average
-Match traing: Match tactics 50% (bar all the way to the left) and tich the box "rest after match".
-Load the tactic in all 3 tactic slots.
-Get a least a 4 star Tactical coach. Maldera (coach) or Tassotti (assistent) from Milan are the very best.
-Arrange a friendly game every 4 days. This way you will have 2 days "Match tactics" training before the match. Then one day rest after the match, 1 day general training (tactical) and 2 days match training (match tactics).
-IMPORTANT: Start personal player training after the tactic is 100% fluid. This way they will spend all of their time training on your tactic!
Through testing i've found that with this method your tactics will be at least 95% fluid at the start of the league.