I did not log anything the first 10 years of kitesurfing (and never since 1979 windsurfing).
But have done it from 2009 till now.
Simply noting in a little notebook or directly in excel, when home again.
Doing it because everybody asks: How often do you go out ? How many hours ? Which sizes are used the most at what time of the year ? What winddirection is it most often and onshore or sideshore ? What boards do you use how often ?
And of course I was just as interested myself (just the natural curiosity - as it has no practical importance to me...)
The only thing I note in every line is:
Start clock entering the water
End clock of water time (for the day/spot)
Kitesizes used (in same order as used)
This is so easy and fast to do, even long after your sessions
What one maybe could or should write too:
Weather (clear, clowdy, raining, fog, hail, snow)
Wind direction compared to spot (degree sideshore)
How many out
Line lengths used
Wind speed makes no sense at all IMO, just kitesizes and boards as they say it all (as you know yourself and weight).
But a field would be fine, with average and max wind speed, as many times you got a local weather station close by.
But one could go on and on...
Because, when you go out, you might start with a big 10 and 12m2 kite on one board the first sessions, and later use a 5 or 6 or 7m2 kite on another board(s) - and you might have surfed around some pointbreaks or similar, to ride at another break for some hours, or going on "trips" before returning and maybe changing kite again to a bigger or smaller, and the weather could often change from sunny to rain, to hail, even snow, and back to clear sunny again, and the wind could change direction of to between 90 and 180 degrees at the same spot etc etc.
So one could often write a whole novel - that would never be able to fit into any "schemes".
That is why I just note the 5 things above - when, where, what kitesizes, what wind direction, what boards, just to be able to get an historically idea over the years, what happens.
Will note wave size too from now on, no matter if on TT or Race or Waveboard