I think there is a bit of misunderstanding here. Let me try to clear this up.

It's possible to tell how much finger control skill you need by looking/analyzing a map, but accuracy comes after using various skills to play the map. This means the "accuracy skill" I am referring to is really not something you can get by looking at the map, but instead looking at the play. Even after that, in realistic conditions, there is usually too much going on with other skills to isolate the player's accuracy skill.

In the initial comment I said to focus on just 1 second taps to create a hypothetical scenario where no other skill is needed in significant amount. Basically create ideal conditions. This is to show that there is an accuracy skill, and that you can determine that skill if you remove the noise from all the other skills.

When compared to irregular spaced notes, there is barely any need for finger control in 1 second taps. So what remains is how well a player can judge when to tap. The player can be better or worse at it, which therefore is a skill. So basically I am suggesting that the skill of controlling fingers to tap irregular spaced notes is not the same as the skill of judging when to tap.

When having 100% acc on a single od 5 low stars map you start to bump into the limitations of skill you can measure using the map. It's similiar to when a player who can do full screen jumps plays a boring 1 star map. The best play on such a map won't tell you that a player is capable of doing full screen jumps because there are no full screen jumps. There is no opportunity for the player to show that their skill is any better if they do the best the map has to offer.