I am not sure why a dive count really matters after the first hundred dives or so, but it sure does to some folks. Ego for some, professional records for others, I suppose.
We once did a SB trip where, to the rest of the group one of the divers seemed to be counting dives in the shower before breakfast! We were all joking because he appeared to be bragging of logging 3 dives, before he even got wet each morning! I know he is still on SB, and I am certain that by now this diver is claiming several thousand dives, but the only one he is kidding was himself.
I was told by one instructor when I was doing a refresher, that anytime you breath compressed gas under water, it should be logged. I tend to follow that, and jot down notes in my log even if it is just helping a friend as a spotter when he is teaching, but 1 session gets one notation, not a logged dive each time my face gets wet, as that one diver I mentioned above seemed to be doing.
The shortest actual dive in my log is 6 minutes to 10 feet,and I certainly logged THAT dive, so it had a record to remember, and to learn from!
It was a solo, night dive, where it felt like I had stepped off of the train platform into front of the express subway, on a Coz shore dive. I literally crawled my way back along the bottom to even be able to return to my entry point in an amazing current that had not been there when I check out the site just an or so hour earlier!
Log what you want to remember, log whatever you have changed and anything that those changes have effected, log anything you may wish to be able to look up years later.
What and how, or even if you log is totally up to each diver, imo.