Ok, I'll go back 30 years here. Lapping is done to help eliminate grinding roughness (and perhaps smooth hard spots) sometimes seen on valve or seat faces. Way back when, and I've done my share, seats were often ground and not machined (at least during rebuilds). Rule of thumb: if a seat or valve appears to have a rough grind surface, then you probably should lap them in. And don't over-do it, you don't want a wide seat else the valve can't shed heat to the seat. I did countless triple-angle valve jobs in an auto engine rebuilding shop, so I have a modicum of experience. Valves themselves are ground with a very fine stone (did a crap load of them on a Kwik-Way), leaving a smooth surface.
Most seats are machined, and have been for a long time. Lapping is usually unnecessary. Here's how to tell...take both valves and place them in the head. Open one about an inch, then smack it closed sharply with your fingers. Repeat this 2 or 3 times, then pull the valve and look at the face. If you see a ring mark all the way around the face, you're good.
On the other hand, if it helps you sleep by all means give them a touch - won't hurt.
By the way, Kohler service manuals are free to download, here's the link for your engine: