These diagrams show an exploded view of weaving done with one tablet, with one hole threaded.
The top diagram is of warp twining with the tablet turned all forward. A thread is on top for two picks, and underneath for two picks. After four quarter-turns, it's back where it started.
The second two show the effect of a reversal at two different points in the turning sequence. A thread can end up being on top for one or three picks.