If you want to often trade then is better to have wallet at the stock exchange. And if you want to just invest and forget for a long time, then it is better for each coin separate wallet. Also I advise to protect yourself as much as possible from hacking and so on.

At all - better wallet, you can control what is going on here without conflicts with exchange, and if you still want to daytrade - you may send some coins already from the wallet to exchange.               

if I do not want to hold the coin in the long term, then of course exchange. And if you keep that cool wallet

Hardware wallet is safer storage than exachange for your tokens. But when you see good price at exchange and want sell your tokens- you will wait until tokens will be transfered from wallet to exchange

To keep your funds in an exchange is too risky, honestly a few thousand dollars is fine, but there is always a risk. Besides, hardware wallets like ledger nano s are not that expensive and also some coins have software wallets that are free to setup. 100k or a million is way too risky, most exchanges still receive problems due to crypto still being a new market so please do store it in a wallet.

I use the exchange for trading.
I use a purse for storage for a period of more than a month.

the exchange is convenient because you can put a pending order for sale and not miss the sale at the right price, even if you are not behind the computer. But it is not safe to store money on the exchange for a long time, although now the exchanges have good very good security.

Purses are safer than stock exchanges, but it is not always convenient with coins to make quick sales. I need to be in any case for a computer. I myself put a call to the block at the right price. When the bell is triggered, I transfer money from my wallet to the exchange and sell at the right price. But the downside is that you need to render the computer very quickly =)

Myetherwallet is nothing negative, it is number one in store token. If you want to store ERC stardard tokens on your smartphone, Eidoo wallet will be a great choice. It is very secure and easy to use and we can easily join ICO with ICO engine.

according to the experience I have ever felt and naturally it would be better if you keep some of your crypto coins in the wallet than on exchanges

I'm feel more secure to store my funds in my own wallet with private seed

If you want to trade then obviously an exchange. If you want to hold then wallet is best as you have total control over your assets. You have the keys to access wallet and you can send where you want.Some holders are having problems getting funds released from certain exchangers