For various reasons, and in various cases, bloat happens. Theoretically autovacuum protects us all, but sometimes it doesn't. Sometimes someone disables it, or mis-configures, or bad planet alignment happens, and we end up in deep bloat. What to do then? Vacuum? ...

Yes, finally! David Fetter wrote, and Heikki Linnakangas committed patch which adds on/off arguments to \timing: