Thinking a bit more about adding extra triggering packages by default the bigger problem is not failures, but the test that pass only with packages from -proposed, because passing test results don't connect packages in migration: LP: #1908508.
The autopkgtests should answer if migrating a particular package to the release pocket breaks anything. By adding extra triggers and not migrating those with the package the tests can't answer that question anymore, resulting more likely regressions in the release pocket.
It is not clear how many test runs are saved by adding the extra triggers nor the negative impact on the release pocket's quality, but I'd like to not have extra triggers until LP: #1908508 is fixed.
Thinking a bit more about adding extra triggering packages by default the bigger problem is not failures, but the test that pass only with packages from -proposed, because passing test results don't connect packages in migration: LP: #1908508.
The autopkgtests should answer if migrating a particular package to the release pocket breaks anything. By adding extra triggers and not migrating those with the package the tests can't answer that question anymore, resulting more likely regressions in the release pocket.
It is not clear how many test runs are saved by adding the extra triggers nor the negative impact on the release pocket's quality, but I'd like to not have extra triggers until LP: #1908508 is fixed.