But, isn't this setup of your's stressful and tedious? Juggling different accounts amongst different CEXs isn't something I can handle, honestly. If I get to a point where I feel unsafe keeping my funds in a particular CEX or CEXs in general, I'll simply quit trading.
It actually takes alot to be splitting up funds into different exchanges. Sometimes you also lose them by yourself as a result of bad trade because you are likely and or probably going to be trading those accounts simultaneously. In such case, if a trade goes bad in one account, it is likely going to affect the other account. It means you will eventually lose that which you are trying to safeguard from incident of all the funds being affected by hack. It is better to reduce the risk by transferring an amount you can lose one time and when you want to refund you do that at a lesser amount. This, the risk is still high with splitting funds and diversifying through different exchanges.
But the good part is that if you are profitable, you may also gain from all the accounts if you are trading them simultaneously and same pairs.
I'm not even talking about the profit/loss here. If you're using the same leverage and the trading fee is the same, there is no difference in putting your funds in a single or multiple trading account(s) in terms of profit/loss. In fact, it's even more of a disadvantage because you'll have less margin buffer for SL. Just too many reasons to frown at this type of setup.
I don't think he trades at all the exchange the same time. He's just managing his asset with basic risk management instead of going all in one exchange. But to be honest, whether trading at all or not, managing too much exchange accounts would be stressful for me too.
If he doesn't trade all at the same time, that's even more tedious, especially if maybe you're trading on different pairs. You have to be looking out for news, making more analysis, etc. As he said earlier, he trades grid which is somewhat automated in most CEXs—that's the only way I can understand how he manages those multiple trading accounts.
I understand his concerns but all exchanges are the same. I would rather move out my coins to a more secured wallet after trade if I'm scared of exchange hack instead of having them divided in multiple exchanges accounts.
IKR, I'd just quit if I started getting this paranoid—guess we're all built differently.