I haven't broken the 2500km+ DIY distance yet. Next year hopefully. But I assume as the rule says a minimum of 200km EVERY DAY. If I want to go and do 2x 300km days I do not assume I have a days rest. I do assume that if I start late on the first day I don't have to hit 200km, as with finishing on the final day. Just that every day in between needs to be 200km or more; that isn't to say I couldn't continue past midnight, have all day off for a bit of sight seeing and a nap, then begin late evening and continue through doing 200 |+100, 'day off', 100 |+200
Why do people ride 600km DIYs? Make it 700 and benefit from all the extra time to have a proper sleep (and go to the pub!)
All this extra time you think you are benefiting from is time when you woukd normally be asleep either on Friday night or Sunday night.
E.g. I tend to wake each day at 7 and go to bed at midnight. So starting at 7am my 42 hour limit on a 600 takes me to 1am on Monday. 34 of those 42 hours are the time I would normally be awake.
Starting a 700 at the same time gives you until 11am to finish, but of those 52 hours I only get 4 more in time I would normally be asleep so unless i can ride at 25km/h non stop for 4 hours I would be losing more sleep than on a 600.
Anyone who cannot bank enough time for a decent sleep on a 600 would be losing sleep on Friday and Sunday night to get a decent Saturday night. Poor trade.
800 makes more sense 60 hours limit means starting at 7am gives you until 7pm on day 3 so you can ride 3 days of 267km in 12 hours each giving ample time to relax overnight.