I think your reply feels like what I got from the piece;

Effort would be the extra strength applied past what is needed to get a reasonable grip. It is “effort” when you squeeze hard enough to bend the lid.

I see other comments talking about dropping a cup if you don’t hold it tight enough but the idea is the baseline is “hold the cup tight enough to have it secure in your hand under normal reasonable conditions” but our default state may be “grip it hard enough all the time so a coworker couldn’t muscle it out of your hands” or “if a door opened in your face and hit it you still hold the cup” and that is the effort - the above and beyond that you don’t need to always apply which can screw up our baseline.

Like the message is we need to be mindful of not going full throttle on everything when low or medium energy / focus / brain activation / muscle activation will do.