Which is all fine by me but, if I was in your situation and saw a trade offer come in I would just reply with the below and say "I expect to get to your offer in x amount of time" or words to that effect.
From my point of view, I operate on multiple platforms and deal with hundreds of different traders so the trade I offer today may not be the one I want to complete in 2 or 3 weeks.
Especially if I think the offer is being ignored I will grab the cards elsewhere if they come up.
Now if weeks later out of the blue you accept my proposal because I am expected just to leave it sitting there for your leisure and I turn around and say "I don't want that deal anymore" I look like the bad trader.
If I knew you were looking at I would be much less likely to acquire the same cards elsewhere or if I did I would inform you and the above scenario could be avoided!
The limited number of people here who have dealt with me do probably realise I value communication and I may even go over the top to say where I am at with a proposal but, I like to keep everyone on the same page to avoid any misunderstandings.