Sooner or later you'll wish you had logged all of your dives.
So what IS a logged dive anyways?
Well according to my dive computer, when I go down to the training platform at 35 feet to tie off the float and heavy rope for the next batch of students. That 3 to 5 minute interval is logged as a dive according to the computer. I disagree, so I don't count it as such. What I do write down in the manual logbook is "PADI OW Training Dive 1" "5 students no problems". If I have a difficult student I will make note of it, but still to me it's only one dive,,,sort of.
In general if I've been down for 10 minutes or more, or if something extrordinary happens (saw UFO had to dive for 2 minutes to avoid possible capture and anal probe), I'll log it as a dive for future reference, bragging rights, or just to recall a trip or event.