
Interesting idea. We don't have many people who need to do this beyond the initial IP warmup phase, which our postmaster team walks clients through, but something to think about. Not sure why you're doing this on the regular?
Also, just to make sure you're aware of this trick: you can always segment a % of your list using a condition with 'Contact ID ends with'... and since it will always end with 0-9, you can create an easy 30 or 40% of your list by saying 'ends with 0,1,2 or 3 for example.