I have been going back and forth with a prospective buyer on DAN.com for several months. We exchanged offers multiple times, I made a counteroffer I was sure he would accept, and the offer timed out. I asked him a couple of questions, which were met with silence. A couple of weeks later, he made the same offer to me, and instead of playing games, I accepted the offer.
When I buy a domain name, I make my payment as soon as the agreement is signed or as soon as the platform and my bank will allow. If I agree to a deal during business hours, I make every effort possible to fund the deal immediately. Some buyers are like me and others drag their feet. When I have negotiated via email with someone over a period of time, we have usually established some sort of rapport. I can get status updates on payment and the counterparty is typically forthcoming. When negotiating via platform like DAN, the experience may be a bit less personal.