i vote 90° for weaving..
and 45° for braiding (plaiting)

if you take a piece of paper, (half the long way-5.25 X11) and cut 3 strips, you start braiding by turning the outside edge at a 45° angle) and then continue that as you plait them, when you come to the edge, and need to fold back the paper to make bring it back... low and behold, the internal angle is 90°.. so the braiding is being done and 45°, and a double turn (180°) gives you a 90° internal angle..

( Start with a 45°bend, weave under and over, come to edge, fold back (180°) and the internal angle is 90°--) and yet, until i did it with paper, i was sure it was 60°! ) Mind you hair and thread and straw are softer, and might not be perfect turns.. but closer to 45° than to 60°!