yes, I was also like that, neglecting to save my 2FA secret key, so I had to wait a long time for the complaint process to deactivate on my exchange account first, and that also took time because the delay made me lose big because I was late selling my coin at that time, since then I learned that I have to save the seeds in several places not only on my cellphone but elsewhere for example on a google drive or flashdisk so that when my cellphone has a problem or is lost I can recover 2FA to access the sites I use especially casinos, usually people will learn from their mistakes
When you experience your first time to nearly lose your account because you forget its 2FA and inside it you have big capital, you would be super panic. Not all exchanges will give you instant or quick support. In 2017 and 2018, exchanges like Poloniex had very poor support with long delayed response to support ticket. It is one of reasons they lost their first position to Bittrex then Binance.
I forgot to mention about another issue when you backup 2FA secret code. You will have two options, with QR code or with character code. I'd prefer to backup both of them but more prefer to backup the character code. Lastly, some exchanges will give you option to print it with a print page contains their exchange information. I don't like this format as it can put my backup under more curious eyes if they occasionally see my paper. So if I print it, I will cut exchange information (of course I must have note that what code is for what account).