I'll address each workout individually, then try to sum it up to the best of my understanding.
Sit ups. There's absolutely nothing wrong with doing situps/crunches everyday. This is mostly because you don't work the muscles with a single rep nearly as hard as you work your chest with a single rep of bench pressing, or your hamstrings with a single rep of squats. This means there is less lactic acidosis buildup in the muscles, less tearing of the muscle fibers, and less stress overall. The advantages of such, is abs with very high endurance, pretty much the only use for abs in MMA is endurance and as a shell over the organs (IMO).
Pushups. Definitely useful in MMA. And if you can bang out 100 every day, that's a real good things. The upper body is where most fighters' muscular endurance fails first, removing that failue from the equation makes winning a lot easier.
Squats. This is where things get very situational. I'll go with BW squats first since the other two exercises were body weight I'll assume squats are as well. Deep BW squats are a good way to develop endurance in the hamstrings, and to a protracted degree the quads, calfs, stabiliazers, etc. However, this does potentially lead to a failure in the joints. The reason most baseball catchers retire is from chronic injuries to their knees from an excessive amount of time spent in a deep squated postion, Bas Rutten also discussed a similar injury he has during his interview on Joe Rogan's podcast. Something to keep in mind, and maybe decrease the number of reps marginally. If these squats are weighted squats, its again a measure of the amount of reps. In this case I would say that squats should be done every other day in that by providing weight you are significantly increasing the trauma to the muscles and joints with each rep.
As a whole, these workouts effectively develop endurance in their areas of effect. However if the goal is to develop overall strength, in the long term body weight workouts are ineffective. Much higher weights than one's natural body weight are needed to develop those areas. Explosiveness can be developed through modified body weight workouts like squat jumps, clapping pushups, etc.
In MMA, there is absolutely nothing more important than endurance. Bas Rutten has talked about this, Chuck Liddell has talked about it. As a initial basic workout to develop those areas these numbers seem pretty solid.
Sig courtesy of that photo-matic magician limba
I went out the way that I fight. I went out on my shield. Thatís it. Done. --Chuck Liddell
My goal is to end my opponent --Carlos Condit