You should know that every case is different.
Nadal was injured with his knee, he has problems with it almost always.
And we saw e.g. wrist injury when the guy missed almost a year, but there is example if someone misses only 1-2 weeks if that type of wrist injury isn't serious..
Also, you can't think that an older guy is more inclined for a long injury. They can be injured more often but it's depending of type, not really the age.
I mean someone who was always injured, more problematic at older age but there are guys who didn't really had injury that often, maybe is has less problems at old age than a bad type of young guy.
I would call Kubot average, he had problems but usually they weren't serious. In last year he missed at most 2-3 weeks, about 2-4 times. But he plays a lot of tournaments, also on singles and doubles.