i just finished my first week of 15's and do one set for each exercise. Im doing the a/b routine so only 6 exercises per day. doing one set of 15 takes me about 25-30 minutes which seems like nothing. would it be a good idea to do 2 sets of 15 instead, or just stick to the 1 set? after 15's i plan to do 2x10 and 3x5. also since im doing the a/b split routine, the complete cycle will be longer then 8 weeks correct?