I've been traveling for work for three years (2 as GM, 1 as PM). I can count on less than one hand the amount of times I've even heard them solicit for volunteers. I've never been in danger of an IDB (although status probably has something to do with that). It seems the very few times I do hear them ask for volunteers, I always need to get to where I'm going on time. I guess I'm in the vast majority! Although the fact that I'm ATL based probably factors in, as well.