On most occasions it doesn't really matter for me, but if it's a weekday (or sunday) start time kinda gets important. In summer most of us are gmt+2 and if we keep those epicly long combos we are going to finish after midnight (don't forget quali ) with the suggested 20:00 gmt, which is definatly too late.
I'm also for shorter distances so we can also use tracks like Aston Grand Prix or Kyoto Long. Maybe we could define something like a race distance like 120 km or 1 hour which should also appeal to more drivers (with smaller bladders).
btw: big no for races on friday / saturday, I have a life outside the internet.