for man/zone i think use of getting tired is a must. there are exceptionally experienced teams, or maybe a team with a fantastic soph class, where this is not the case - but i suspect at least 90% of man/zone teams should have at least a player or two on getting tired. especially zone, where you fatigue slowly, and have minimal risk of hitting the low fatigue. somewhere around tired is where fatigue starts to really matter, and you don't want to be playing in very tired. note: maybe zone/fb and man/fb teams, this does not apply for, but i was really talking about non fb teams.
with the press teams fatiguing so slowly, i almost never use getting tired. it depends on your situation. if you are 11-12 men deep, sometimes i use it. at 10 or less, i basically never use it, because you are going to be hitting tired (minimally) anyway. better to spread things out a bit, and hit it later. still, running 11-12 deep, its rare i use getting tired, because my feeling is you dont really get 100% fatigue back before subbing in, like in the other defenses. so, what happens is you get a few extra minutes, but those cause you to be more fatigued for all but the first few minutes you play. going from 22 to 25 minutes is just not worth it to reduce the quality of play for not only those 3 minutes, but also 12 of the 22 you already were playing. in man/zone, you would usually get back to a solid fresh before going back in, so the few minutes you gain will be at a more fatigued state, but you aren't hurting the minutes you already would have played. and usually, that is worth it - a getting tired starter is very often better than a fresh backup.