[Sopater]

Both windows are in the same room, one facing the motorcade coming toward him and the other with the motorcade going away. In either case, his exit would be out of the room and down the stairs.

True, but the farther away you are from the focus of attention, the better your chances are of being undetected.

[Lagmeister]

Well... yes, I agree. But in this case both distances were rather close with people packed all along both sides of the route. People pointed to both the grassy knoll and the windows. My guess is that two shooters were angled for the going away shot if Oswald - for some reason - failed to take the 'toward' shot.

I think the reason Oswald missed his first going away shot is that he was rattled... which is why he didn't take the toward shot. I'm just guessing that whoever shot Kennedy was the second shooter on the going away route.

Oswald was a piss-poor shot who was unnerved all the way through - and, in fact, was a conspirator as well as a patsy.