I'm stapling 5/16" hardwood floor using 1" staples. I just measured
how deep the staple goes at 45° and it requires a subfloor 1/2" thick.

My motivations is that after stapling the hardwood strips upstairs on
wood underlayment, I'm concerned that gluing them on concrete is going
to be not only more laborious as would increase the waste.

I've found several strips which were a little bent up or sideways and
I'm afraid that the glue would allow for such strips, unlike when
stapling.

Thoughts?

TIA