For the caveman film, "Spit", It took one and a half weeks of basically nonstop work. I had to mute the camera audio which is all they recorded, and rebuild everything from scratch. Their ADR also consisted mostly of grunts and other random caveman sounds so the easiest part about that was that there wasn't a whole lot of noises that seemed like they needed synced with moving lips. I got lucky on the chicken. They had recorded some chicken sounds so I used them. The river clip in the reel, I liked my river sounds so I highlighted them. You'll notice when the chicken's POV goes under, the sound of the water changes. It simulates the sound if you had your head under water with it swirling around you. That was a standard low pass preset on the river sound I was already using.

I found a creative technique at making grass and dust footstep sounds also (for footstep foley without bringing in real grass and making the old lady angry). Take a plastic shopping bag and a towel, set it on carpeted floor, place the bag underneath the towel, step on the towel with the mic placement in between where your feet will hit at about 6 inches away for clean sound

So yeah, I had to invent some methods and work with what I had.
All the sound effects, thunder included, were recorded with a Zoom H4n (sometimes used an AT8035b on an input). Mostly it was the 2 on-board cardioids at the top. There was one evening of a rare Texas thunderstorm that I sat out in the street in my car and recorded the thunder. I don't think there is such a thing as cloud-to-cloud lighting in Texas

Really good stuff on that reel!