Getting in on the current sidetracking of this thread, I'm terrible at reps. My first 20-rep squat was at 50% 1RM. Back when I was doing Starting Strength I was even worse -- I got so accustomed to 3x5 that to even approach a 6th rep in my working sets meant a significant reduction in weight, and after an injury I found myself doing 3x10 at 30% and being thoroughly gassed, as well as very sore afterwards.
Over the last 8 weeks I've been focusing on 10 reps per set with squats, starting with 5x10, and then diealing it down to 3x10. On Monday I aim to hit 10 reps at 100kg (when I started at 5x10 I was doing 60kg), and then taper off with probably some doubles and triples before trying to hit that magical 3 plate 1RM in the second week of November.
Back to the original question, I wouldn't do 20-reppers with deadlifts, but I might do it with RDLs. I would do it with bench press, overhead press and rows.