Have a look at §15.8.1, Creating Snapshots, in the user manual PDF, for better options on taking snapshots of larger groups of documents. The yellow tip box in that section may also be useful to you. I like to give bulk snapshots a common name so I can know there may be other snapshots related to an edit elsewhere. The Snapshots Manager tool makes it easy to fetch a list of items that have a snapshot of a particular name.
Another tip is to check out §15.8.5, a few pages down. The second bullet point, which can have snapshots created for you on all edited documents automatically, is a different way of thinking about it as your snapshots come after the edits instead of before—but if used routinely the effect is much the same. A big advantage here is that only the snapshots you actually need are created. Blanket bulk snapshots on a whole section can result in snapshots you don’t actually need unless you really do edit everything every time.
Personally I use a mix of both! It depends on the situation, but I like having the safety net of the second option. It is a little peace of mind once you form the habit.
I’d like to see here (and for other actions like changing state or labels) that all selected items would be considered.
See §10.4.7, Setting Metadata to Many Items. 