Hi Berend,
To my knowledge this is not customary. E.g. Subversion has a completely independent release schedule from any of the distributions. However, since rules and regulations seem to change regularly in the accounting business (but not in version control) it seems appropriate to at least provide minimal fixes.
Also, accounting data is typically very sensitive data. While version control data may be too, one would expect technical people to be able to secure it (or to find people to do so for them). But everybody who runs a business needs an accounting/ERP package, even if they're technically left handed. My idea behind the proposal was that we should facilitate packagers to create releases as easily as possible.
Though a different approach could be to estimate that we have 18 months between releases. LTS distributions such as Ubuntu LTS and Debian typically run for 18 months as well. This would require us to keep support for 36 months after initial release or rather 18 months after the follow-up release. Since this reasoning is independent of individual distros, it's probably a better criterion?
Bye,
Erik.