I go out on the local trails at least a couple times a month, and I've never once aired down. When I was stock it was partly because the truck came with nitrogen inflated tires that I didn't want to let out (part of the dealer's "Sierra Package" or some BS like that, which I got them to take off the price) and partly because I don't have a compressor to refill the tires.
Most of the trails I frequent are not designated OHV trails, but old mining or power company roads that are no longer maintained. They can get quite rocky at times, but nothing that I couldn't handle with my stock TE. It's also worth mentioning that 95% of the time the trails are bone dry and tractions is not much of an issue.
My question is, when does it become strongly recommended to air down? I understand the advantages of a larger tire footprint and that the tire can conform better to rough surfaces, but I haven't been in a situation where I felt like that was necessary. I guess it would be nice in rock gardens from a comfort standpoint and might reduce wear and tear on the suspension a bit, but it just seems like a hassle.
What conditions/situations do you guys air down and what advantages am I overlooking?
Typical trails:
This is on the rougher end: