How long do you wait?
If I initiate a trade through Pinpics TA, I don't hold anything because replies through Pinpics are rare these days.
If I accept a trade through Pinpics TA, I will hold the pin no more than 2 days.
Of course, I've had people come back to me a week or so later claiming
My mail went to their junk folder or their dog was sick or whatever and ask if I still want the trade. And if I still want the trade, I am always happy to say yes :0)