Not every day is good for day trading

so, make sure only trade when you think it is really a good day trading opportunity.

For such day tradings, holding it over night is very rare, unless you are very positive tomorrow you can sell it at a higher price. Like yesterday, I hold QID over night.

On the other hand, swing trade try to catch a longer trend in order to maximize the profits.

So:

ST - to maximize the profits
DT - to balance the risk, reward and always position yourself better for next good opportunity

A trading account combined both will be really nice for a sustainable growth. Finally, remember such a trading account is only small part of the diversified investment portfolio.