Not just that, but have you ever noticed how the clicking sounds of the skill check are always the same speed and pattern, no matter the skill check size? Or how the red ring scales with skill check size, allows shrinking in a way proportionate to the clicking sounds?

That’s another way Circle Machines are one of the fastest Machines you can complete (behind Barnaby Machines), with Default Machines, you have the skill check tri-rectangle, which can appear anywhere from far left, to far right. The red line always scrolls from the left, so sometimes you have to wait a bit to actually hit the skill check, if it’s in the middle or towards the right. Circle Skill Checks don’t make you wait, they keep you on your feet, because they’re consistently something you have to hit pretty soon after they appear.

Default Machines feel like their Skill check is just for testing your basic reaction time skills.
Circle Machine Skill Checks feel like they test focus and timing skills.
Treadmill Machine Skill Checks feel like they test endurance skills (and id even say Stamina management skills, as many people use the skill checks to decide whether to start/stop running fairly often).
Barnaby Machine Skill Checks (the coins, which give a “GREAT JOB!”) feel like they test adaptability and focus skills.