First off, ask yourself, how far away is your pro or amatuer fight? If it’s more than 2 weeks away, feel free to spar/exercise to your hearts content. Don’t spar to the point where you constantly have nagging injuries, but spar to a point where you are winded and feel like you put in some work.
Some martial arts you can do more often than others. Jiu Jitsu, wrestling and Judo, you can do fairly often, as your body/brain don’t take a tremendous beating. Muay Thai and fingerless glove MMA on the other hand is another story. That being said, you need to spar Muay Thai and MMA if you want to be comfortable in a fight. So find a sparring partner who knows how to throw punches quickly, but not powerfully, and don’t train with people who beat the hell out of you. It’s the worst!
Two weeks away, start to taper off your sparring. The last thing you need is a hurting rib or a recent concussion to spoil your win. Focus more on cage/ring grappling, getting your opponent there, and keeping him there or on the ground.
Now we are within 5 days of the fight, workout a bit everyday, but no more than an hour a day, and make it gentle. The day before a fight, keep your reflexes sharp by training with a sparring partner but only light form and speed work. This will keep your blocking reflexes sharp, and you can practice some counter punching. No more than a small sweat the day before a fight (unless you are cutting weight, in which case make sure you hit weight).
This is my formula for when we are training our pro fighters.
If you are ever in Salt Lake City, and are looking for some sparring, come check us out at Factum CrossFit and MMA in Sandy, UT.