Are you positive or negative on casinos asking for log-in frequently or do you feel unsafe in putting your login details every time?
Such behaviour will make me have a negative reaction towards that casino. Being logged out all the time when I have not even closed my browser will make me think there is something suspicious about my account that the casino is investigating, which makes them log me out, which will end up giving me a mixed feeling about whether I should continue gambling there or not, or if they are probably waiting for the right time to disable my account with an excuse best known to them.
Unless the casino is open, ask on the login page for how many minutes I want to stay logged in, and if such an option is enabled and I happen to click on it after the exact time has been exhausted, getting logged out even though I am still on the browser is understandable, but this really makes this appear unsafe in my eyes, which will trigger a mixed reaction from me.