yes, i agree on this, if you want to hold your coins for the long time better to transfer it on your wallet. because in the wallet is more much secure than any other exchange even if this exchange is on top or not better to secure your funds.
Well, move on to your wallet so they are safer, do not put them on the wallet of such trades very risky for you, maybe they will lose if you do not control them. Depending on the person but most people moved to wallet to hold longer.