Ubuntu requires a reboot way too often

If you run updates manually before rebooting, it should not require another reboot afterwards. It would only require another reboot if there was another update pending that was installed after you rebooted.

The most likely reason a reboot is needed is to switch to the newly installed kernel brought in by the update. For almost all other updates, affected services can be restarted without rebooting.

Most of the time, you can ignore this and not reboot; but be aware that if you don't reboot, you will be running the older kernel which may have security holes that are fixed in the newer kernel.

Note that because you are running a non-LTS version of ubuntu, there may be even more updates, so this would require reboots more frequently.

If you are super keen on not rebooting and were running an LTS version of Ubuntu, you could try the live patch service which tries to upgrade the in memory kernel without rebooting. But this very occasionally fails and you still need to reboot.

Note also that as long as you are aware of the consequences of not rebooting, it is possible to just turn off the reminder.