I have run a bunch of D37 timekeepers, and after years of desert racing and not giving the enduros a second thought, I couldn't believe how much fun and how challenging they were!
The first year I used a stop watch and put a piece of tape over the hours so all I could see were the min/secs, and a rollchart and stock KTM odo. It took me a couple races to finally get it together, but I started zeroing checks. The problem was, as I got more comfortable I started going faster and it was hard to see the small watch and odo. I coughed up the $ and bought an ICO checkmate, and it's like enduro for dummies. I can see why the old school purists don't care for them. It helped me step up my game, and at the age of 49 I scored one 9th OA and one 10th OA finish as well as winning my class.
And don't forget about tiebreakers!
Your head could explode if you try to take it all in at once