I have loved small engines since childhood and a big reason has always been the cool putt putt sound. I have always loved low idles, whether on a small single cylinder or on a big v8 or on a big diesel or on an antique engine.
I think the lower the idle on a Garden Tractor, the more it feels like a tractor and the more classic feel it has. I'm not so into the unchanging 3200 rpm buzz or high idles of many mowers, especially later ones. I only tolerate it when necessary.
So I like to get all of my engines down to the lowest possible idle. I think it is a sign of a good running, well-tuned engine, and clean, properly-operating carburetor and ignition system when you can get your idle putt-putting really slow.
On that note I think this thread could simultaneously contain a discussion of HOW TO GET YOUR IDLE AS LOW AS POSSIBLE on various engines. I don't mean crazy win a contest slow, I mean nice practical slow.
Now my one reservation with running low RPMs is of course Splash Lubrication. I know there are many factors which vary greatly between different engines like where oil needs to be splashed up to, whether oil vaporization is a need for the particular oiling system, the design of the oil paddle/dipper/slinger, etc. The obvious thing is that low RPMs mean less splashing of the oil, less oil gets splashed up to higher areas inside the engine and less oil vapor is created. For example, the Overhead Tecumsehs, use oil vaporization to lubricate the valves way up top. Vaporization is another level above mere splashing IMO.
I think what would be helpful in understanding more about this potential danger to a valued engine, is some real concrete information or analysis of the issue. If anyone knows of some scientific or some quality garage-mechanic science on this or some educated/experienced thoughts, it would be great to learn from this and discuss it.