I had a 2 hour coding project in a language I'm familiar with - entirely based around a sub module that I've never used before.

Maybe 2 hours should have been enough? I don't know - with the stress of writing under time pressure ( I had a new sympathy for contestants in cooking shows ) and complete unfamiliarity with the module, I was pretty impressed that I submitted something that passed the unit tests.

Then I got rejected with the implication that I wasn't using good OOP principles. OK, my decision to store JSON data as a byte array was unorthodox - but it worked without a lot of coding overhead. I thought it was pretty clever frankly.