No one's arguing here, they're just stating what they think is best, and why.
GiGi could live in a 5.5gal. Hell, I've kept her in it for months before (moving, vacations, and such). She stay in 1 square foot, when she gets too hot, she climbs onto her hammock. In her 5.5gal we usually put in her strawberry hide, put down slate, water bowl, cactus, hammock. All she uses. So each gecko is very different. On the other hand, there's Lucie. Very active hunter, and will jump clear across the 20 long after a cricket. She's never in the same hide for more than an hour.
I would say do what works for your individual gecko. We're thinking about moving GiGi into the 5.5gal permanently to make room for another baby on the way who's closer to Lucie's size. She's small, a dwarf, and loves to be in her 5.5gal. She's rarely ever in her tank anyways. When she hunts, she's more likely to do it in a 5.5gal, than in a 20gal where the food can scatter more. She doesn't need multiple hides, she never uses them (bash all you want, but GiGi is an oddity, and doesn't classify [in my eyes] as a leopard gecko. She thinks she's human...) and when she sheds, we soak her and shed her ourselves to prevent her from biting herself (she can't shed, even with a humid hide, due to missing brain functions).
So it all just depends on the gecko. I do think more than 1 in a 10 gal is pushing it, unless they're babies.