whilst not necessarily to the degree the "super fit"
guys here are talking about but Crystal Brook did run sliding scale races with later model bikes doing more laps than earlier ones. I was happy with 4 laps as it did test the old bod but made you feel good about it coming in. At my pace that was around 9 mins or just over.
And I do have to point out again - yes the Nats are the pinnacle of our sport but if you want to ask members how many laps they feel happy with (or time) them also find out how many are racing for sheep stations and how many are out for a ride. May be (and it has been discsused at length also) you have longer title races and shorter "support" races?
??