Hello, welcome to eyewire.
So accuracy works based on consensus and will dynamically (real time) change every 60 cubes you do. I can see from your profile that you have equally much over and under colouring. That means that you are both adding segments that other players have not and missing segments that other players added.
Neither of those is a bad thing on its own if it's in a small %. As explained in this vid:
So you may be adding segments that belong in the trace that others missed and you may be missing merger segs that others included. Of course with a high % in over/under it may also mean that you're adding segments that don't belong and missing those that do.
I would suggest watching these:
and reading this:
They are really helpful.
Furthermore eyewire is almost like a 3D and more advanced colouring book, you want/need to colour within the lines/borders of the original dark blue (default colours) given piece(s)/segments and then continue colouring inside the borders of the additions you added until it either ends in cube (if it's smooth + round and doesn't have jagged edges or flat surfaces it may be correct) or touches wall. (Pro tip here: just because a trace touched wall doesn't mean it ends there it may continue along the wall, change plane with a, d, left/right arrow keys to get a better view of the wall(s) and the trace in general.)
There are some tricky bits in some cubes like merger gaps:
and black spills:
but these are not that frequent.
Finally if you are unsure of a trace and you think you want help don't hesitate to ask in chat, scouts and scythes can look at a cube if you give us an ID (next to top left corner OVERVIEW | ##### <-) and mentors can watch your cube if you ask in chat and give permission. (we are good vampires we only enter a cube with permision )
Hope these help.