I'm trying to determine how often to show a prompt to users to update their browser.
I suspect most users will come to the site once a month on average to pay their bill. Some will come hardly at all because of auto pay. Some more often at certain times in their life to look at account settings and their profile information.
I'm, of course, focusing on IE. IE6 and IE7 just aren't supported, IE8 is unofficially supported. We check it but don't freak out if there's a minor bug here and there. Our computers are set to IE9 so that's where our focus starts and we move on up from there.
I think I have three options:
Show it every other month. This way, the users who come monthly don't see it every time. The users who come less frequently will probably see it every time, but it's still not often simply because they're not on the site much.
Show it once and never bother them with it again. My gut tells me that if I ask my usability study participants this is the option they'll choose. As we know, some users can't update their browser because of work or something similar and some just don't want to.
Show it to them every time they're on the site so they're reminded that the site might not work properly. I just don't want to annoy them with a pop up every. single. time if it's bad practice. We all know how annoying pop ups are. Even if I did just a little bar across the top like this site (https://browser-update.org/) I worry it could be too much if it never goes away.