Guidance for removing features in continuously-updated CRs

There have been at least two recent working group charters that have opted to continuously update CR drafts without intending to move to the Rec stage:

https://w3c.github.io/charter-drafts/sw-2020.html
https://www.w3.org/2021/03/proposed-bbtt-wg-charter.html

Both charters mention that new features need (at least an intent for) two implementations, tests, and implementation reports

When things progress to Rec, there is a well-defined point where the implementation report shows whether two or more implementations are interoperable, and we have a well-defined process for dropping features that do not meet this requirement.

I think it’s unclear when (or if!) features should be dropped from a continuously-updated CR. I think it would be good to have some loose guidance that each group can adapt for their own workflows. Perhaps something like:

1. Features without two implementations, tests, and a passing implementation report should be marked at-risk before updating CR
2. Features that continue to be at-risk at a CR update should be re-evaluated, and dropped from the CR if it has become less likely that they will ever pass an implementation report.