Does rotating running shoes actually help preserve them? yes or no?

30 years ago, yes. Today, with all of the carbon dioxide in the air, no.

A shoe is tested under dry conditions for things like shock absorbing...I've noticed that after a warm/hot day running/sweating the shoes are still damp the next day. So I bought 2 pair to let them dry out before running in them again.

The materials do have a shelf life...but you should cross the 500-1000 mile usage barrier long before the shoe's components break down due to age. Do they break down if always damp? Probably.

Maybe a little.

Each time the shoe is used, midsole foam compresses a little. Don't know if anybody's ever measured how much, if at all, the foam "bounces back" to any degree. If the shoes are excessively wet from water or sweat the rest day probably does them more good.

Better benefit probably goes to the feet, which will be stressed in slightly different ways in another pair of kicks.

I run a lot in the snow, and my shoes are constantly getting icy and wet. I leave them in front of a low-speed fan overnight to dry before the next day's run. Maybe this isn't a good idea?

No. Your festering feet will soil anything and everything!

I rotate different models of shoes because I think it helps my body to run in something slightly different and vary the stresses on my body.

I don't think it makes a noticeable difference in the longevity of the shoes. It might have made a difference with the foam in use 30 years ago to give it a day between runs. I don't think that's true today or at least significant enough to matter.

I agree that it mostly helps with smell be giving moisture additional time to dry up. Midsole feel changes more due to temperature than it does from running-related compression. Rotate to keep the shoes smelling fresh or to get a different feel for your feet, but outsole and midsole rubbers are extremely resilient in the modern era and unlikely to be very different between days unless temperature is a factor.

Rotated all my shoes running casual and dress. Plus the running shoes were in a three rotation with new shoes getting a first break-in on a light day and every couple of 1>2>1 cycles after that so I always had at least 2 pairs raceready at all times.

Two pairs of rotated Alden Oxford dress shoes still look good after 20 plus years. Granted not an every day shoe but They got their workout because I dressedup a lot because the GFs job (fundraiser) has a lot of dress up affairs to drag me to.

More unqualified opinions wrote:

I rotate different models of shoes because I think it helps my body to run in something slightly different and vary the stresses on my body.

I don't think it makes a noticeable difference in the longevity of the shoes.

^This. I think rotating shoes helps reduce injuries by varying the impact forces of running. It also helps in identifying when shoes wear out. One pair will still feel okay, but when I switch or add a new shoe to the rotation, I can tell these old shoes have lost their cushioning.