For the electron wallet I see no wrong about it. It's a person choice to choose any type of wallet of your choice but when choosing be security concious. For the Cex you said I think it's better you save your coin in DEX rather CEX.
You can use noncustodial wallet for the savings, not decentralized exchanges. Decentralized exchanges works in a way to be used also for the exchange of coins and finally the coin will be sent to an address on your noncustodial wallet.