40% is a bit low mind, normally I do the same thing but I tend to leave it between 50-65% depending on the length of time between games on the 2 different days, brings you back up to around 95% for kick-off, I tend not to get a lot of injuries for some reason, had 1 game where I had 3 injured but other than that its been mostly 0 or sometimes 1 per game with the odd training injury once a week.