Should trigger locks always be activated when a power tool is in use?

Unless it's a long tedious job, I try to avoid using trigger locks. - - Many years ago when using a large Makita belt sander to clean up old wood flooring, my trigger finger got numb, so I used the trigger lock. Just a few minutes later someone came in behind me and in turning , I lost grip and this big sander went flying across the floor into the next room, ploughing a huge scar in a part I'd already finished ! - A lesson I never forgot !