My warmup for deads will often look like this (if I'm going for, say, 180kg):
60kg x 3
100kg x 3
140kg x 1
160kg x 1
But for bench, if I"m working with 100kg, it'll be more like this:
20kg x 5
40kg x 3
60kg x 2
80kg x 1
90kg x 1
Just what I've sorted out over the last almost-two-years or so. It's probably an individual thing, from everything I've seen and read.
So in other words, if what you're doing is working... awesome.
edit: Sometimes I'll do an "overwarmup", more likely with squats than anything else. Just a heavier single (or more than one) than the working sets, then back down to them.