Hey, typing while I practice...why didn't I think of that? Seriously, ask any who've met me, they will tell you the sad truth is I have no life. So plenty of time to train and still annoy all of you.
Paul, I also wonder about all those breakfalls, although my first sensei required his students to take breakfalls exclusively over rolls once they had been taught, so perhaps that is the case where you are...if so, get help on the falls or consider a dojo change...
You can do what I do if I'm too injured to train, and go watch...you learn a lot, and it would rule out that question of 'is this just an excuse to sit around the house...'. Another thing might be do everything you can do (make sure it is OK with your instructor first) and sit out the rest. I came close to taking off the end of a finger a couple of months ago, and if we start doing weapons in the middle of class I sit it out (can't grip well yet), then get back into it once the weapons are put away. Or if we are doing a breakfall required technique, I either ask for a softer throw for that one side, or grab a beginner who won't throw me harder/faster than I can take (ie, I just don't slap with my injured hand).
Finally, number of hours is not the key, it's what you do with them...as I pointed out, anyone who's suffered through a technique with me knows frequent attendance has not done much for my ability...I'm just a slow learner (luckily, I enjoy the process, so it's ok I don't make much progress).