I delete cookies fairly regularly.
Uname and p/ws are not deleted, but "trusted"status on my bank logins are.
So I load up the login page, uname comes up as an option when I click the box;
Pw comes up the same way on SOME sites but not all;
I always have to enter certain characters from my 'memorable info';
then I have to have external confirmation via one-time-password eg by text;
\\then I can "trust" my device, which means I don't have to worry about the external confirmation step - until I delete cookies.