it's much harder to come up with a polite excuse ........ to terminate the visit when they're in your home. You can't make a vague claim of other plans or give a reason you need to excuse yourself and leave, you have to kick them out of your home............. having the visit at your home actually puts a fair amount of the power in their hands because it forces you to be an impolite and ungracious host if you want to control the length of the visit.
I guess this depends upon what type of relationship you want to have with them after the visit is over.
I remember a visit I had with a couple of elders who shepherd called upon my house one day, I suspect at the behest of my wife. The reason I think it was at the behest of my wife was that she intimated to me that the call would be for her, but left me in the room with them alone shortly after they arrived.
This was just after one of their assemblies where they were equating themselves with being the modern day Ark (IE Noah's Ark).
During the visit, they were trying to corner me on some asinine point about agreeing that salvation was only through association with the organization (WT Society) and that I would be a fool to not be a fully active member. Exasperated, I finally told them
"Look......we can sit here and discuss the Bible all you want, but, I will not have you guys attempt to corner or beat me over the head with it."
After a stunned silence from them, they hurriedly terminated the visit and left.
.....without even a handshake or a closing prayer.