My track dont have sportsman, pro or any ranking class. Everyone races eachother. We generally have 3-4 10 min heats qualifiers and the c final 15 mins, B final 20 mins, A final 30 mins.
Or during a national or special event/ raceday we have up to 7 10 min qualifiers a 20 min C final, 30 Min B final and a 1hour long A main. (Which i love but god do your legs ache after words)