But one of the latter ones was kinda crazy. I am thinking about the one where Shia placed a flag inside some wooden cabin (in Finland iirc), and they managed to find it based on a pattern of the woodgrain[0].
0. https://www.dailydot.com/unclick/4chan-shia-labeouf-cabin/
So they tracked jets flying overhead, and combined that with what birds and bugs they could hear. And that got them the location.
Tracking jets flying jets along with the rest of the things you mention only helped with narrowing it down to somewhere in the viscinity of Tennessee[0]. After that, there was no progress whatsoever until that geotagged tweet containing a photo of Shia with a diner waitress (she was the one who tweeted it, as it was a typical "i took a photo with a celebrity i just met" tweet), which narrowed it down to a speicific small town in Tennessee. And only then all the fun stuff with driving around and honking occurred.
While tracking flying jets was a cool idea, it ended up being a dead-end approach, as it didn't help with narrowing it down beyond "Tennessee and adjacent areas". And the geotagged photo that eventually led to the flag location didn't rely on overhead jet paths or any of that, as the geotag was fairly sufficient.
0. http://wikimapia.org/36787915/He-Will-Not-Divide-Us-Flag-Sit...