Sledge
I even think the active cd needs to have at least 6 races in that season to take effect but I could be wrong
Wow, you've either been playing this game for a long time or are being advised be a veteran manager.
Just to be clear, this used to be the case about 4 years ago when the Elite cars had a 1-100 design range and a start of season cap of 50dp per attribute. You needed a CD to be active for 6 races in order to achieve the cap at the beginning of the next season.
Since the design range was increased to 1-200 and the number of next season dp generated by a CD per race was reduced and the cap removed this no longer applies. The CD strength is now primarily used to improve research, next season start design is only a secondary consideration in leagues which forbid resetting between seasons.