As I said, there are all sorts of factors. For instance, lets say you train five hours a day for six days, that would be a total of 30 hours. Depending on the art that might or might not be a problem. For an art such as Tai Chi which is not all that physically taxing on the body, there are lots of people who probably could pull off five hours a day. Intensive training in an art such as Muai Thai, on the other hand, five hours a day for six days you could very easily hurt yourself or at least you would experience diminishing returns. As I said, there are all sorts of factors.