Depends on where you are in the ecosystem. If you're running your own service, the only flavors that matter and the ones you're using.
If all my machines are FreeBSD 4.11, I don't care if my scripts don't run on Linux or Solaris or SCO or even FreeBSD 4.8 or 14. I might care someday, but not today.
Maintenance scripts need to run on all the versions in the fleet (usually), but setup scripts can often be limited to the latest version, because why not use the latest OS if you're setting up a new machine.
If you're distributing software, yeah you've got to support a lot of variation. If you're at a shop that runs lots of different flavors, you have to support lots of variation. But a lot of people just pick a flavor and update the scripts as needed when the flavor of the day changes.
Trying to keep dependencies and running services as tight and small as possible helps a lot with keeping up to date on security. Don't need to update things that aren't installed, and may not need to update things that are installed but not running (but sometimes you do).
If all my machines are FreeBSD 4.11, I don't care if my scripts don't run on Linux or Solaris or SCO or even FreeBSD 4.8 or 14. I might care someday, but not today.
Maintenance scripts need to run on all the versions in the fleet (usually), but setup scripts can often be limited to the latest version, because why not use the latest OS if you're setting up a new machine.
If you're distributing software, yeah you've got to support a lot of variation. If you're at a shop that runs lots of different flavors, you have to support lots of variation. But a lot of people just pick a flavor and update the scripts as needed when the flavor of the day changes.
Trying to keep dependencies and running services as tight and small as possible helps a lot with keeping up to date on security. Don't need to update things that aren't installed, and may not need to update things that are installed but not running (but sometimes you do).