100% power can mean many different things.

Most glass tubes have a max rated power, a max recommended power, and a max recommended power for long life.

The controller also has a 100% setting (some only go to 99%), which only means that it is sending a signal of 100% to the laser power supply. The laser power supply must also then be tuned properly to drive the tube at the desired output power.

The only way to really know what power the tube is operating at is to use an ammeter, then you can tune the power supply so that 100% on the controller is equal to 100% of your max desired output power - which should be less than the tube is capable of in order to allow the tube to last a while.

It seems that a popular shortcut is to just tell people to run at 80%, but without an ammeter you have no way of knowing what that really is.