I'm fairly certain this information is not published by Microsoft within the bulletin information or elsewhere. What happens is the installation of any patch will write the reboot required flag in the registry by the installation executable, which is then reported back to the SMP by the patch software.
I therefore assume every critical or important OS patch requires a reboot and have set up my process so that my critical servers have a client patch remediation policy applied that will install patches but not automatically reboot the system to apply them (every other system has a policy that will automatically reboot). I can then see which servers have to be rebooted and can plan the reboot process for each one as necessary, closing apps properly and 'out of hours' (which could be automated by tasks). I created a report that shows for any patch policy the number of success, fails, pending reboots, pending execution, reschedules, etc.
I also use auto cadencing of patch installs, automatically applying the one policy to a sequence of target groups in turn, with my critical servers being the last to be patched. It ensures all goes as smoothly as possible and with the minimum amount of work, while keeping me aware of al that is happening.