Recently I transferred from USDT from my Independent Reserve account to Kucoin.  Unfortunately I was stuck using the Eth2.0 network and that cost me USD 20 for that transaction.  Pretty steep. 

If I use a credit card and transfer fiat to Kucoin it's $30 in every thousand.. Ridiculous.

I've only just figures out that the cost of transferring cryptocurrencies depends on which crytptocurrency I transfer.  Is that correct?

So I would have been better buying say Dogecoin in Independent Reserve then transferring that to Kucoin so I didn't have to pay that ridiculous fee.

Is my logic correct here?  What is the cheapest way to transfer cryptocurrencies between exchanges.. Is one coin cheaper to send than all the rest?

Thanks