bulgie 

OK, 1 mm is a bit of an exageration. It could theoretically work but it's complicated. Most axle ends have around 1 mm of chamfer, so if you literally had 1 mm of axle stickout, it wouldn't even touch the frame at the full 10 mm diameter. But if you cut it very square with no chamfer then yeah, 1 mm could work. But you pretty much never need to try that when going from 5-sp to 7-sp, there's enough axle there.

I mentioned "Sheldon Brown approved", but here's the actual quote: "As long as you have 2 or 3 mm sticking out on each side, that's plenty." (It's here, halfway down the page)
St. Sheldon did not sign off on one mm! I'm pretty sure he did experiment with a wheel with zero stickout, where the only thing locating the wheel in the dropout is the 5 mm QR skewer, and he pronounced it strong enough. But a PITA to center the wheel in the frame. Maybe useful for someone with vertical dropouts who wants to run fixed or SS. Sorry I don't remember where he wrote about that, maybe on a forum, mailing list or rec.bicycles newsgroup.