My laptop has a bug related to Fn keys not working without go to sleep mode (related to a BIOS problem see here https://www.virtualconfusion.net/function-keys-not-working-on-e15-gen-2-linux/).
Yesterday I updated my BIOS to the latest version (1.17) and now my laptop does not need to add a crontab entry to have the function keys working.
To update your BIOS please follow these instructions (this at your own risk).