Not necessarily a huge flaw and indeed it’s a method I used for a long time too - but what it doesn’t really help with is when there’s a breach and one of your

Not necessarily a huge flaw and indeed it’s a method I used for a long time too - but what it doesn’t really help with is when there’s a breach and one of your passwords is in a leak. What do you do: make (and remember) an exception and the second choice function? Or change all your passwords so an amended function still holds true for all sites? With a password manager you just change the breached one and that’s it.