Preparing in test forum and 7 hours downtime cause of recount, thumbnailing and a bit testing
I was having a guestbook-like script running to entertain the people while updating... they always panic when the sites not fully online
I now have made several diffs to patch a new version with my (php)code hacks - so the update from 3.5.3 to 3.5.4 was done in 30 seconds