There was virtually no queueing, and I had absolutely nothing else to do. So why not spend 30-60 minutes, my time wasn't valuable in any way at all, I had nothing whatsoever to do all day other than sit around and BS with friends. It also meant that I got a bit of exercise walking to the bank and back.
I've known of guys walking quite a way to a different exchange bureau to probably save 30 Baht.