It depends on how they do the scoring.
Following the way most track events work, the winner of each event gets the most points, then second place gets fewer, and so on. If you skip an event you get no points, so it's the same as finishing outside the points.
There's a relatively new international track event (held at world cups and worlds) called the "international omnium" where it's 5 events (3 TT, 2 mass start) held over the course of a day. In each event, first place=1 pt, 2nd=2 pts, 3rd=3 pts, and so on. Lowest total score at the end wins. Riders are DQ if they fail to complete an event (there's no way to apply a score, especially if more than one skipped any event). So you can most definitely have an omnium where you have to complete all events.
The chance of points going only 3 deep is pretty small-- track omniums, where the max number of riders on a 250 m track is 24, give points 5 deep (7,5,3,2,1). I'd expect a road race to award points pretty deep- the points classification rule for stage racing gives points 15 deep unless it's otherwise announced in the race announcement/race bible.
Last edited by bitingduck; 03-13-09 at 06:08 PM.