I think Knots act in pairs, too, namely Madrigal---Covenant, The-place-in-Force-Ten-From-Stoneheim---Somewhere in the Western Barrier, near where the Deciever's camp was in TFL and Rhi'Anon---Another Knot which has since been lost. All recorded instances of Knotting have either occurred between one of these pairs, or archmagi have used their own force of will to "pull" troops through a knot where the archmage is, or to "push" troops out of a knot where both the troops and the archmage aren't.
btw, each pair of knots has its own glyph on the pylons, although for some reason, the glyph on the Force Ten Knot changed between TFL and Myth2. As to why, your guess is as good as mine.
