...
Anyway, I don't fully understand such a situation.. Like when I need an exchange, I put the exact sum to the exchange, do the operation and withdraw it back to my wallet or wherever I need it. Why should I leave something on the exchange?
Or you can use some coin swap service for quick swaps... I have the amount on the exchange that I use for trading, it's not big, and I don't wish to pay withdrawal fees after every trade I make. I am an amateur trader, and I don't trade with some big amounts so I don't feel some big need constant moving of my trading capital. What you are saying is fine and advisable for people who trade with big capital.