I assume you're using IOs 14? The password manager has a new feature built in that will check the stored password against a list of known hacks. There's a website you can check (haveibeenpwned.com) was/is run by Troy Hunt (a security guru) and you can check passwords or accounts for references to previous hacks. For instance LinkedIn was hacked and all email and passords leaked unencrypted. So if you use same password at linkedin and anywhere else it's potentionaly compromised any account with same email and passwird combo.
Ashley Madison, adultfriendfinder, adobe, linkedin, yahoo, loads of companies have been exposed. Never re-use passwords and you'll be much safer. That way if one service is compromised your password wont match for your email or spotify or worse online banking.
There's no need to change it every few days - you've probably just used same password in multiple accounts or it matched one in the common list.