PTFE has good load-bearing properties in thin films.
It doesn't see much heavy load use in thicker sections, like bushings, though.
This is due to two factors; it is both fairly soft, and very slippery - so its machinability is pretty awful.
The other one is that it does creep [undergo plastic flow] under load, so thicker sections are more susceptible to this effect.
All PTFE sprays are not created equal, too - I've just found the Jaycar product to be better than most.
