It depends on the prey size what grouping I do. For the xl rats for my redtail, I either seal them by themselves as one serving, or more often I add the 2 medium rats for my Colombian rainbow and normal bp since they are all on the same schedule. The small rats get sealed in pairs (2 snakes on these) and the weanling rats will either be pairs or small groups of 4-6 that I open as needed (2 snakes on these). The mice I group by how many I expect to feed at one time (currently 8 per bag for that group of snakes).
When I seal per expected feeding group, it makes dropping them in a container of water for thawing easy. The only drawback is if there’s a snake in shed which means I either have to open, separate, and reseal or risk wasting a rat. I don’t worry as much about not using the mice as there is typically someone willing to eat an extra mouse.
As a side note, I use my vacuum sealer for food as well. It just gets wiped down with either rubbing alcohol or disinfecting cleaner after I use it on rodents. Realistically there isn’t anything that gets on the machine from the rats, its just my own internal ick factor at play. lol