How long would a beaver persist in building a dam if someone kept returning each piece of wood back to where the beaver took it from?

My uncle had a problem with beavers damming the creek behind his house and I forget why that was a problem, exactly, but he had livestock that used it, I think. He’s a smart guy who does a lot of humorously dumb stuff, to everyone’s amusement- like exploding oil into his face working on an engine, or falling into the creek while trying to fill up a camp coffee pot, or running his camp stove in his tent, gassing himself out and ending up rushed to the hospital. He tried playing catch with his pre-teen granddaughter and she hit him with a softball and broke his rib. He was just a one-man comedy show there for awhile.

Anyway, he took an axe, sledgehammer and shovel and broke up the beaver’s dam and hauled off all the pieces. It was such hard work, he needed a nap, and by the time he woke up and came back out to admire his free-flowing creek, the beavers had rebuilt the dam, exactly like before! I like to think they putting on the finishing touches, just as he showed up!