Bittrex is the most problematic crypto exchange. It had previously required verification of the identity,
otherwise it would be impossible to withdraw your money.
I understood that bittrex asked for the verification of your identity if you made withdrawals greater than 10 bitcoin, if I am not mistaken.
Not really because mine was also first not verified but after few small withdrawals they stopped withdrawals even less than 0.1 BTC and asked me to verify my account. It had happened very long back and my verification was successful instantly. After that, I don't have any issues to trade on this exchange.