I know for me I couldn't currently handle 6 days a week of that sort of training. It really depends on the person. Discipline is great, but I know plenty of people who have burned themselves out with that level of training and little recovery. Of course it depends how hard they go in the kickboxing classes. Although my days of late have been 3 days karate and 3 days weight training, but it was a nice mix . Now I've scaled it down due to it being too much actually!