Overlap path length calculation

During calibration I have noticed the top infill has small holes when filling a cube at 45 degrees but only in the section where the path length is increasing, when passing the middle and the path of getting shorter the holes disappear.
This made me wonder if the infill path length is calculated at the short side of each path hence under extruding when hitting an angle >90 degrees and over extruding when <90 degrees?
Can this be compensated some way or is it a trade off I have to accept?

Added a picture of the phenomena at overlap 0.07
And a comparison of (bottom up) 0.07, 0.1, 0.15 and 0.25.
Increased overlap does improve the quality but Cura does not produce any holes at all and further increase will probably introduce other artefacts.