So, this has been rounding my mind for since i started to believe in crypto.
I there exists plenty of wallets and various types, but this is a questions focus on trading wallets, and dealing with exchanges.
What happen when you are not using a wallet provided by the exchange (eg. Bittrex), but then you want to sell a coin the coin ASAP so you dont miss the peak.
HELP!
first stop calling what exchanges give you "a wallet" and your confusion will be resolved.
in other words what exchanges give you is not a wallet, it is an account that you have some numbers on which represent a value. you don't have access to those funds the exchange does and they allow you to use these funds.
so in order to do it fast you need to have funds in your account which is a number in their centralized database. you give up control when you deposit but gain speed.