I'd say that on my 15 years career I had many more tickets related to bugs that I needed to troubleshoot locally than issues with migrating to a new version/release of a distro. To be honest it's been 10 years since the last time I had a major issue caused by distro migration or update.
it's harder in all the way you describe, but it's much more likely the software will survive migrating to the next debian/centos release unchanged.
it all boils down to the temporal scale of the project.