map pilot - wrong duration and bateries estimates, ver 5.3.1

hi,

I am trying to get the estimated time for a project of 855 hect,

I set the mission type to normal, altitude 80m, connectionless, overlap 80/75, then I set three drone speed to see the variation on duration / batteries for these three speed,
the thing is, the app is not giving results in proportion with the variation off speed, as it is supposed, for lower speed ---> more duration and battery changes,

here the results the app is giving:
6 m/s -- 1,261min  -- 67 bat
5 m/s -- 1,024min* -- 9 bat **
3 m/s -- 1,956min  -- 55 bat*

I need to calculate for several speed to take into account the duration for changes in light conditions