I think part of this is CYA. CAN-SPAM (US) gives them 10 business days to stop the emails, so they allow themselves the full time. I've never gotten an email

I think part of this is CYA. CAN-SPAM (US) gives them 10 business days to stop the emails, so they allow themselves the full time. I've never gotten an email more than an hour or too after unsubscribing from legitimate emails. Edit: Although byoung2 points out a case where you would get the emails for a few more days at least.