If you enter a 0° heading for the first A+ line, that one will indeed point true north and if extended, will hit the true north pole. All subsequent passes from that one will be exactly parallel and will miss the north pole by the distance you are from the original. If you are working on a mile wide field, you'll hit the pole with the first line but miss it by exactly a mile on the last pass. All your passes will be parallel though.

Bear in mind that the guys who surveyed and set the section pegs had to deal with this also, so most section lines don't run true north either. The measuring I've done here, seems to suggest that the Township line is true and intermediate section lines between the Townships are off just a bit, so most of the sections and subsections can be square.

If you're @ 52°, that puts you 3082 miles south of the pole. Someone who knows something about trig can figure out how much of an angle a quarter mile (or half, or full mile) will be in 3082 miles and that will be your variance for different widths of fields will be. Degree heading won't change with length of field -- it's dependent on width.