Totally depends on your goals. If you want to buy a house soon, you gotta invest short term where you can make great profits in no time. But if you are investing for your retirement, it has to be a long term investment.
Short or long doesn't matter. What matters is that you invest wisely.
I agree with you, the most important thing is to invest wisely. Personally I like both short and long term investment as they will serve different purpose.
Definitely this is word of truth