7
Actually, it is just extra sessions in the database that stick around, and how long before the session cookie on your client expires. Only dangerousif you have hundreds of users, but much less annoying than having my session time out because I got a phone call interrupting a post. It does however confuse the hell out of the Who's Online block...
It just happened again this morning. I started a post on this site, got interrupted and when I hit submit...
Whack!!!
My public site has timeout set at 1 hour, but my test site has it set for 1 day (because I hate logging in, and nobody lse uses it.)