How long can you hold a plank for?

That depends on how heavy the plank is.

Long enough to nail it

Great answers you’ve gotten I was a little slow because I had to go get a plant to try holding and I’ve found that all the answers are correct for me also I can’t hold it all night will someone nail it already.

Out of what kind of wood? If pine, then for a long time

Lots of comedians in the comments huh

About 1 minute 20 seconds, it would seem. Gonna add them to the workout routine. 🤔

I can't hold the plank in my life for much longer...

Two minutes, but I'm old