Comment by gpm

When I've reached for stacked PRs (in the past, not using this feature) it's precisely because I've split my change into smaller PRs being merged individually.

I've just written those smaller PRs at once, or in quick enough succession that the previous PRs weren't merged before the later ones were ready. And the later ones relied on the previous ones because that's how working on a feature works.

The earlier PRs are absolutely reviewable and testable without relying on the later ones. The later ones are just treating the earlier ones as part of the codebase. I.e. everything here looks like two different PRs except the timing.

An obvious example would be "implement API for a feature" and then "implement UI that uses that API". Two different PRs. The second fundamentally relies on the first.