My current ratio is 100% in cold wallet and 0% in crypto exchange.
That's what I like to see. IMO acceptable ratio is anything below 10% on exchanges, but currently I also have 0.
I see no point in holding money on exchanges, unless you're either a day trader, or own very little. People who don't do any of that and still hold significant amounts must be lazy or scared to learn self-custody.
It's a huge risk nobody should be willing to take.
I usually do not support keeping your Bitcoins in the exchange wallets, but with the current surge in transaction fees forced me to keep a specific amount in my exchange wallet. I simply cannot afford to make multiple transactions with such high fees.
Then don't make multiple transactions until the fees go down. Group them, use lightning, or keep risking the money. There's always a choice.