niko is right, no need over 120%, even 100% also good enough if you manipulate the draw
For my own fun 2 season before I power train my 3 attackers (2 wingers 1 St) to 150% (first time in top11 carrier); they playing good but keeping them over 100 or 120% in every season mean draining resources
Keep in mind, as players get more old and high star, their gaining goes slow