@michmoor depending on your environment and traffic flows you could adjust those.. but its much less resources to just leave a state open then create a new one..
But depending on how many clients, what sort of traffic patterns, how many different connections they make.. You could run into a scenario where 24 hours might be too long and you run into state exhaustion. If that was the case you could adjust the default timeouts to try and mitigate such issues.
edit:
that being said normally when client is done with a conversation it would close the session with fin, fin,ack or even a RST.. Odd that its still open, but if the device is off and was removed from the network before it could close the session then yeah could stay open for 24 hours. Unless the other end closed it.