How many snapshots are kept, and for how long?

Thirty, on a sliding scale — one a day for the last week, one a week for the last month, one a month for the last six, then the most recent fill whatever is left.

The scale is the point. A flat "keep the last 30" would give you thirty copies of last week and nothing older, which is useless for a mistake you notice a month later. Tiering buys you long reach without storing more.

Thirty is a ceiling and cannot be raised. The Keep control offers 10, 20 or 30, and 30 is the top of it.

Storage is not the reason to keep it low. A full copy is taken weekly and compressed; the ones in between store only what changed since that full copy, which is typically a fraction of a percent of its size. Each one still rebuilds into your whole account — a restore reads the full copy and one set of changes, never a chain of them.

You can also take one whenever you want with Take one now, which is worth doing before anything you are unsure about — a bulk import, a big tidy-up of your playbook. Manual ones are labelled Manual in the list.