Lol DG - there is counter-offer !!! a seller is in the drivers seat. 

Reducing time does not automatically mean that. 

If a buyer sent a make an offer to me and a timeline of 12 hours.  If I didn't see it until after the 12 hours, if the price was agreeable before the offer expired, I could easily send counter-offer proposing to further extend the timeline term ???

It is so not as limited as you indicating.