I always keep my funds fully secured because i can't keep my funds in any exchanges like fork delta, etherdelta.com and other decentralized exchange. But some centralized exchanges binance, kucoin, and houbi also can you keep in those.
If some one is a daily trader and require funds then using multiple secured exchanges is recommended . Also for people who are long term holders and do not require it daily then better to store if offline so that you do not have to worry about the stolen or theft that might happen .
This is what am i doing with my coins, I often use various exchanges to avoid getting hacked or lose funds. Even for my bitcoin i have bits stocked on many exchanges in case any on my exchanges fails to secure it then i have my fall back but i guess the disadvantage of using that kind of strategy is that you are paying much more fees than it should be.