I understand that SpaceX ephemerides they publish are more accurate than the typical two-line element set. But the TLEs using the SGP4 propagator typically have

I understand that SpaceX ephemerides they publish are more accurate than the typical two-line element set. But the TLEs using the SGP4 propagator typically have errors on the order of 10s to 100s of meters [0] (and more, the further you are from the ephemeris time). Is the estimation really enough to get to down to the meter or sub-meter accuracy? Is that why it really requires 8+ satellites to get a good fix, i.e. it takes that many measurements to reduce your variance and GDOP? [0] https://conference.sdo.esoc.esa.int/proceedings/sdc6/paper/41/SDC6-paper41.pdf https://conference.sdo.esoc.esa.int/proceedings/sdc6/paper/4...