You sign in and you forget to click remember me and you think, oh well, better check that next time. But you never do.
Muscle memory is great and all that but it makes you go username-tab-password-enter before another thought ever enters your mind and the nuisance of the frequent sign in is sustained.
So I plead for every decent site to let us ask to be remembered at any time after sign in. Ideally somewhere near the Sign Out button.