If you only need to run the tests you affect, and only need to sync and update files touched in your CL, external changes are generally not impactful, sync & su

If you only need to run the tests you affect, and only need to sync and update files touched in your CL, external changes are generally not impactful, sync & submit is a quick process even if people are submitting things elsewhere. It's only a problem if someone submits a file you're touching, in which case you just have standard merge conflict issues.