I've been a Netflix member for a couple years. When I send a disk back on Monday (assuming it's not late Monday), they get it Tuesday and ship out to me same day, which I get on Wednesday, even though they estimate Thursday on my account info on the website.

I'm sure the speed depends on where you live in relation to their closest facility. Their main HQ is in Los Gatos, about 10 miles from where I live, but they have strategically located facilities across the US (number of those unknown).