That factor, more than any other, is what causes me to view this poll as hinky. The single day shifts in the poll report, require single day shifts 7 times bigger. Drop Trump by 1 point takes a 7 point drop in a one day sample.
Looking just at the female/male breakout, the drop today is ALL MALE! That's weird too. So is the general contour of the African American graph.
All of those sudden moves require much larger single average moves, among what is supposedly a (mostly) fixed group of people polled. My bottom line is I don't find the poll credible.
Either that, or it's as you say. People treat the question like "what would you like for lunch today" and give their answer about the same amount of thought.
Trump must have had a really bad day or two after the tape came out (6-7 point drop in one day like you suggested) for this more than one point drop to happen.
This poll usually only moves in tenths of one percent one way or the other in one day, not more than one percent.
The GOP never Trumpers are having another tantrum and have green lighted people to withdraw their support for Trump. That makes polls useless for a bit, IMO. If they get back on side Trump will be fine.