Federer has not had many problems with injuries, so it's natural he would take considerable less MTOs.
Originally Posted by TennisCJC
Nadal is the MTO GOAT.
Djoko is 2nd on the MTO GOAT list.
Murray is good about MTO's - rarely takes them.
And, Federer is the excellent - I think I only can remember 1 or 2 in 10+ years.
A player don't have to be injured in order to take the MTO, in case you didn't know. If a player decides to delay the match to regroup or weather the storm, he can call MTO anytime. The umpire has no idea if a player is really hurt or not anyway.