A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Position-Finding
From: Peter Monta
Date: 2018 Jul 8, 08:59 -0700
If you can reliably aim your sextant at a point on the horizon that's due north or due south plus or minus a few degrees, within ten minutes of noon, and measure the angle between the Sun and that point, the angle that you get will stably match the noon altitude (or 180-that) for a convenient, extended period of time around local noon.
This might apply equally well to time sights. With the Sun near the zenith, and using a point on the horizon that's known to be nearly east or west, a time sight will be stable.