I have removed and replaced the factory screws numerous times and never re-applied anything.
I believe in frequent thorough inspections which would ID an issue such as loose fasteners.
If you decide to re-apply be sure to read warnings about what some type of uncured threadlock can do to plastics in the vicinity of use.
If you go back to no prop guards remember to use the stock screws,the prop guard ones are too long and will destroy the motors. You probably know this anyway, but worth repeating for noobs as it is a common mistake.