DA Aquamaster:...I also use my own custom log book pages where I have a checkbox for "solo dive" as well as for "deco dive", both of which the DM is free to frown about if he/she wants...
Solo, deco, deco mix, cave, doubles all added to custom log. Unfortunately I haven't had the pleasure of seeing a DM reaction because no one ever asks to see my log book!
I also log every significant dive. Even 13' for 3 minutes like DA, if a recovery, etc. Otherwise, probably not. However, anything over 20' will be logged regardless of significance however short a dive, especially if I'm doing 4-5 dives in a day for several days or a couple deco dives a day for several days. Any information that could be useful to DAN or the chamber, should it come to that (it shouldn't), will be in my log.