48 actual hours of work during the 9 days this Jam will last is more than 5 hours a day on average. For the ones that have a full-time Job and/or studying or doing other stuff is not going to be easy to maintain that rhythm anyway and they probably won't spend them all.
At least on my case that I'm already working 9 hours a day and doing other stuff too, adding other 5 hours on top of it is simply not going to be possible, so on my case (and I'm guessing is the case of many others) I'm not really worried of consuming more than actual 48 hours of work here.