It's not "one day = 24hrs" it's "one whole reset day". Reset time differs with your real world location but say it was 3pm & you got your 'ban' at 4pm. You would have to wait until 3pm came around again before your 24hr day started to count down. As a result your ban would be 23hrs plus 24hrs.

If your ban started at 2:55pm your 24hr day would start at 3pm, therefore your ban would last 24hrs & 5 minutes. That's how all other bans work so I imagine this is the same.

Hope that makes sense & helps you out. =)