I think I have seen a guideline on this and it depends on the number of teams that are there. Like at the Royal they call top 15 for example.
Most contests here will call the Top 10 for all including overall, but trophies/money start at 5. 10 through 6 is a 'call' and 5 through 1st is a walk. A couple contests have given trophies through 10 in the categories, which is very cool, and one contest gave $50 for 10 through 6 which was nice. At least you could buy yourself some dinner afterwards.
I also don't like the top heavy contests. The Sam's club series is very top heavy with trophies and checks for top 3 only. They only called from 7 overall too, which was a bummer. Anyone in the top 10 deserves to be recognized and cheered on. We love to cheer on our friends as much as we like to hear our own name called. Ok, maybe not quite as much, but you know what I mean! LOL
2011 CBBQA Rookie ToY - 6th Overall, 2012 American Royal Invitational - Huminie's Hogalicious BBQ