jg, welcome to the forum!
Yes, the activities are cumulative whether not not they are an overnight campout.
However, a certain number of activties must be overnight campouts.
For Tenderfoot, campout one overnight.
For 2nd class, campout two more times to meet the requirement of three (count the one from Tenderfoot).
For 1st class, campout three more times to meet the requirement of six (count the one from Tenderfoot and the two from 2nd class).
I say campout as much as you can!
We will and do campout at least once a month as a troop. The way I read the requirements I felt it was a cumulative number since they allow you to do all 3 ranks at the same time. I was just wondering if I was interpreting it correctly. This is our first experience in Boy Scouts and it is way different than Cub Scouts.
Thanks for the reply.