Just had another readthrough of some of the posts, and wanted to point a few things out
There are bacteria in the water, though you are correct in stating they are predominantly on surfaces, HOWEVER, if you remove their food (That's to say, the ammonia), you're going to kill them. On top of that, if you swing the water parameters around, the bacteria are even slower to adapt than larger organisms, and that can then kill them as well (Which means even fewer bacteria to process waste in your tank.
As to size making smaller water changes irrelevent, twenty percent is twenty percent regardless of if it's a 2L or 2000L tank, and in terms of reducing ammonia, it will have a positive impact, as you are going to have effectively cycled the entire volume of the tank within five changes, but without having massive swings in the water chemistry that the lifeforms within can't cope with.
And cycling being irrelevent? No.
Cycling is the line between your tank being a healthy biosystem and an unhealthy death trap. From my own experiences, not having a tank cycled is the most dangerous thing you can do- in January this year I was (for both health and life intervention reasons) unable to do water changes for around 8 weeks (Yeah, I hear your gasps of horror...), and it was the cycle that kept the water parameters optimal throughout that period. Conversely, our goldfish tank couldn't establish a cycle, and despite doing water changes on a daily basis (Trying so many different methods!), it got to the point where we had to dismantle it due to the effect it was having on its inhabitants- and that's goldfish, who are a lot more hardy than axies.
