I always thought running was overrated to tell you the truth. I'm not sure it helps me too much. Boxing is a much more of an upper body sport and IMO you could probably build up better upper body stamina by going several minutes on a heavy bag rather than by doing all that runnning. I think that's why you get a lot of heavier fighters who don't do much roadwork and still have loads a stamina for a fight. David Tua is one example of that.
boxing is not an upper body sport, the muscle you use the most is boxing is your calves, your always bouncing or steping. Thats the reason you need to run. Its not just for fitness its for leg conditioning aswell, and short sprints for explosive power. You need to use your legs to get into position to punch and out of the way of punches. Boxing requires full body conditioning. If you want to be a boxer, you have to run.
Eh, I don't see what would be wrong with running everyday. I jump rope everyday which probably puts more stress on your legs. It's not like you're doing track workouts haha
running every day is not wrong at all, however I think it´s best to listen to your body, if you feel tired one day just don´t run that day. Somedays you can run shorter somedays longer. But it does make a big difference in the ring if you run or not. The predator
My boxing coach used to tape a towel around a 24 inch 2x4 and make me push it across the gym floor non-stop for 5 minutes at a time. Basically you just get in a bear-crawl like position, both hands on the 2x4, and use your legs to push you around, and your upper body for balancing and stabilization. You wouldn't believe what simple **** like this will do for your stamina and endurance.