passwords and login names

I read article that said you should have a different login name and password for every thing you do on the Internet and you should replace them every 30 days! After using Keychain for the last month I've got a couple dozen entries. That means if I added no more entries to Keychain, I'd be generating ~250 password/login pairs each year - not going to happen.

Speaking of Keychain, is it secure? I can't see anyway it would be much help in the scenario described above.

This article further explains the sad state of affairs:

30 years of failure: the username/password combination - Ars Technica

Well, I don't see the Passcode combo coming to light with usernames..it wouldn't change the look on un/pw..it's the same! Besides, I find it's easier to remember a word than a set of numbers. As for Keychain, it is secure, provided you don't go hunting for malicious stuff on the internet.