It's because so far I am only considering replacing the nodes slowly, one at a time, mostly in order not to hit any soft limits that may be defined on the accou

It's because so far I am only considering replacing the nodes slowly, one at a time, mostly in order not to hit any soft limits that may be defined on the account(like total number of instances), but also in order to give the user the chance to stop it in case things go south for whatever reason during the evaluation, since as I warned, this thing is likely full of bugs at this point.