I have done hundreds+ of an x-ray exam called Small Bowel Follow-Through (SBFT) as an X-ray Tech which involves swallowing a fairly thinnish barium/water mix. The protocol of imaging was to take a few shots of belly after drinking then, for next hour or two, take pics approx every 15-30 minutes (depending on progression of emptying shown) as the stomach empties into the small bowel.
The vast majority of these exams generally took bewteen hour and half to two and half hours, fwiw. Anything longer was usually due to lack of adequate peristalsis and/or gastric-emptying dysfunction (for whatever reason).
It was not unusual to wait and image the colon somewhat by having the person lay in certain postionsthat let that happen in minutes, not days.
Also, I’ve had an ileostomy glued to my belly which empties from the terminal end of my small bowel. Most mornings, I’ll drink some coffee and eat some cereal (etc) and within an hour (if not much sooner), I can see the output in the bag that indicates it was my most recent meal. I’ve also done this with peanuts as they leave lots of palpable ‘bits’ - same result(s).
Some folks can take longer for the food transit through bowel, of course. But to say that the food has not travelled through the length of bowels for days flies in the face of GI studies by X-ray. A person’s colon can hold onto ‘useless’ fecal matter for awhile after a meal, but it generally transits MUCH faster than people think
I’ve also done many Nuclear Med studies involving gastic emptying and bowel transit using solid food(s) like scrambled eggs or sausage/toast (with Tc-99 mixed into it) - same stuff/times with normal bowel functions.