I have a quick question about physical preparations for beast. DS has been going to crossfit for the past 3 months and is really doing well there. He runs 4 miles each morning before school and has been consistently around 28 minutes for these runs. He is out on his first ruck march right now to begin breaking in his boots. He is carrying a backpack with 30lbs of sand and his route is 5.5 miles. What would be a good or satisfactory time for a 5.5 mile march? I am thinking that he could ruck every other day and do crossfit on his off-ruck days? Or would it be better to bag crossfit and just max his push-ups/sit-ups/pull-ups? I don't want to seem like a drill sergeant, but he is gung-ho and I want to give him good advice. Thanks for any input. GO ARMY!