Testing packages 1 by 1 finds any bugs and the exact package that caused it immediately, but you could just upgrade all of them and see if it fails. If it does

Testing packages 1 by 1 finds any bugs and the exact package that caused it immediately, but you could just upgrade all of them and see if it fails. If it does a git-bisect could find the exact package that causes it. Seems optimizing for the happy path (nothing breaks) could save some time.