As far as I can tell, the snapshot logic works by looking at the amount of transitions. This is not really helpful when there are minimal, but potentially significant mutations over longer periods of time.
Example: a client adds and changes a couple of records every couple of days. He accidentally deletes something and sees that the last auto-snapshot is from a couple of days ago, created before the last mutations.
I think it’s wise to create at least one snapshot a day if there are changes at all. Airtable is external memory and to think back and come up with what you’ve done a couple of days ago can be pretty hard, if not impossible.