Alright, I'll bite.
Personally, it depends. If I'm actively trying to offload a card, I'll usually see who needs it and submit multiple trade offers. If there's no dialogue within a week, and I've made a fair offer - money in/money out is equal, I'll assume there's no interest and cancel the trade.
Another scenario is if I message someone who has a card I'm looking for and I say, "see if there's anything you like in my tradelist" type thing. In this scenario, I'll wait longer because for all I know they may need some time to browse through my tradelist.
Also it's worth noting that most user on here (myself included) are far less active on the weekend. I may check it briefly and thus be indicated as "active" that day, but don't be fooled, I'm not active in the sense that I'm using the chat functions. Since mail doesn't happen on the weekends, what's the rush?