Not real sure what ur question is either. But I'll take a swing at an answer for u. I agree with Chris N. that if ur just starting out u should emphasize technique (1-2's are good to start with). As for as time on the bag u should start out with 3 rds. x 3 min. 1 min. rest period.

Don't worry about trying to wail away & kill the bag. Get ur technique sound. During the last 10 seconds of each round it's not a bad idea to throw punches straight thru the bell (left,right,left,right,etc...). U can also build this drill up to 30 second but not untill u get a little further down the road.

Hope this helps. Good luck.