How does changing your password every 90 days increase security?
Some sites require users to change their password every x days. For example, at least 3 online banking system requires me to do that. Does this mean the admins assume the password could be hacked within the x-day period?
Isn't regularly changing passwords riskier than having one permanent strong password? For example, if you change your password regularly then it means there is a higher chance you will forget it and now you have to store it somewhere (aside from your mind, like a physical paper hidden "under your pillow" or a secret folder in your computer) therefore it increases the possibility of password leakage. Well as if you have just one really strong password hidden in your mind, it can't be leaked.
For simplicity, this question is assuming an average user doesn't know or want to use password storage apps like Keepass since it has its own drawbacks like password portability/computer crash/etc.