Personally (though apparently a common experience):
Hmm, let's try this SS-thing once, for a laugh.
Decide never to do it again.
Sometime later, give it another chance (actually, it wasn't that hard, thinking back).
Start to ride SS a fair bit. Stop mentioning it, leave it to others to spot they've just been beaten up the hill by someone with 27 times fewer gears.
Discover that on hills too steep to ride, SS-fitness means you can run the rest of it faster than others can ride.
Finally, go back to gears, and find that riding up the steepest, nastiest bit of local upwardness has suddenly become amazingly easy.