There's real logic. Your grandmother is also partly right :)
For bowls and everyday tins, a light coat of oil is the workhorse - films evenly, releases cleanly. Lightly oiling your counter for kneading beats flouring it too, because extra bench flour quietly tightens the dough.
Butter earns its place two ways: an even butter coat conducts heat smoothly for uniform side colour, and for sticky SWEET breads it's non-negotiable. Babka gets the dual grease in our course - butter first, then oil - because sugar plus moisture makes enriched doughs weld themselves to tins.
Butter-plus-flour is for wet cake batters that need a wall to grip while climbing. And baking paper isn't cheating, it's a clean substitute in straight-sided tins - it just can't help batter climb or brown the sides the way a greased wall does. Pick by product, not by loyalty.
