If you are still there, is there any reason to read the patches in two directions for the same line? I'm just using one direction and it looks the same to me. Seems to me if you have a nice flat clean target and you aren't getting any error messages that should be fine?
There is no reason to read a line twice unless you are using doing a duel measurement (with and without UV cut). Otherwise, the unit measures something like 100+ samples per second so you get a good averaging per patch. You can move left to right, then on the next row, right to left.