I do UOA on my pickup, and used to do it on my wife's 4Runner. The runner is not used for towing or anything difficult, so once I established an OCI I quit sampling.
The diesel probably doesn't need sampled as I change it at 1 year anyhow, but it's nice to know where it's at when I hit 7500 miles. 1 year is 10-12K miles, and I have gone as much as 30K miles on my oil when the truck was my DD, but since it doesn't see much easy use these days it doesn't get to extend as far.
I don't run dino, so I've never sampled it. The cold flow properties of synthetic are enough for me to run it, everything else is a bonus.