I am currently open if someone excellent comes along, but am not actively looking, so I only poke my head in most days and read the emails. I am chatting with one guy but its been slow and I don't think either of us are wildly interested. In any case I am on less than 5 minutes a day I would think, maybe a little more if you count reading the emails as well, but not much more.
When I was more actively looking, I made sure I updated my profile a little or answered more questions at least weekly to stay on top of the lists, and got a ton of traffic as a result. I also looked at profiles actively myself. So I spent a good bit more time at it. Maybe half an hour a day?