Used to overfill some of our older vehicles on purpose as they were known to use some oil. In the case on a trip if they were to use some there would be be more capacity before it'd get low. My dad ran our old Dodge van 1 quart overfull for 33 years with no issues until we sold it. I don't buy much into the oil foaming, crankshaft whipping the oil thing. Not all of the oil sits in the oil pan when its running like it does when it's shut off. A surprising amount of oil rests in the cylinder head/heads, oil galleys, etc when running. I don't bother on any newer vehicle but I know it won't hurt a thing if I add a bit much on accident.
A few months back I was spinning the oil pump of a Ford 390 on the engine stand priming it with a drill. I only put 3 quarts in to start. It sucked all of that up and it sat in the heads/lifter valley. 4 quarts it sucked air after 10 seconds and lost oil pressure, 5 quarts worked but still sucked air after a while. 6 quarts of course was fine. I can only imagine what it would do if it were low on oil and cornered hard. This was at 70 degree temp with 10w30 oil, so not like it was overly thick taking forever to drain to the pan. I know a lot of newer engines are physically a lot smaller and less oil can be held in the head area but still, similar things will happen.