Frank
There's nothing capping stats anymore so it's all races of the previous season to maximise the Strength stat, or leaving and rejoining during the season break for the same effect.
Frank has already explained, the cap has been removed, so in terms of total design points for the start of the season there is no longer any advantage to be gained by employing multiple CDs.
The two reasons you might still want to use more than one CD is either you want a more balanced design at the beginning of the season or you want to swap CDs during the season to maximise research. However, swapping CDs for research will most likely leave you with a sub optimal design balance so you will then most likely need to leave and re-join your league with your best CD to reset the design.