That's great for him, but that doesn't mean squat when we see alter queries taking 1+ hours on fairly small tables.
I've done alters on the vBulletin (5) node table on my TINY dual core atom with 3+ million node tables in under an hour. Same goes for post/thread/users.
I pestered digitalpoint on twitter, his user table alters are mostly "quick", and he has about half as many tables as you do.
Further, being on an SSD, if the DB is actually being hosted on the SSD, 6+ hours for a million rows is just batshit insane. SOMETHING is wrong with your configuration.