Depends on the traffic for me, if it looks like I'll be slowing down soon, I'll let it get to 3,000rpm before shifting, otherwise I'll let the truck slow down on its own without having to rely as much on my brakes. Other than that, I usually shift between 2,500 and 3,500rpm. I think I've gone above 6,000rpm a few times trying to pull out into traffic at bad intersections while nearly crapping my pants. Last week, I was in one of those situations and I ended up spinning out through first gear, partially through second, and I chirpped the tires in third. I have no idea what rpms I was shifting at, but I do know that I didn't crap my pants.
I'll be the first to admit that I have been hard on my truck, yet with driving like that every once in a while, and wheeling it I still managed to keep my stock clutch for over 100,000 miles.