My RPI's (3b+ and 2) works for days/weeks/months without the need for reboot.
if this keeps happening you can try to kill kodi.bin process (it will restart automaticlly) via SSH.
If after this all works normally my guess would be its some problem with KODI itself (rouge addon would be a good guess) - i made a remote shortcut for this for various needs. (you can check the log file , with/without enabling debug log)
As for you question for scheduled reboot , you can define a cron job for either restarting or killing kodi.bin - but i would not recommend going this way as its not really needed and you should find the cause in KODI itself instead.