I have noticed that sometimes SNAP finds update for, e.g. s1tbx.
Is there a specific release cycle for updates and bugfixes for the different tool boxes and how often do they happen? I have tried to look for it but could not find anything.
There is no specific release cycle for the updates. They are released when a meaningful number of issues have been fixed or even a single serious issue.
For the major releases of SNAP and the toolboxes, we aim for having a release every 6 months.
In the near future we will post a roadmap for SNAP future developments for version 7.0 and beyond so that users have more visibility of the current plans.