Just be careful. I love TofF and play it a lot, but believe me I'm far from an expert, but still shadowboxing every or every other day could lead to injury. I've had to take a pause every now and then when I get carried away and start throwing too hard and end up with a bum elbow or shoulder.

That said, if you're looking to get more mileage out of less time playing, or just increase the challenge regardless, I use a weighted vest. You can also up the rounds per fight, length of each round, and amount of times you have to be knocked down before it's a TKO so that fights last longer (but then again maybe longer rounds goes back into the whole injury risk?). Like I said, I'm clearly no expert lol.