It's long been said that standard damping adjusters aren't very effective. The reality is slightly more complicated. It's fair to say that, as far as road riding goes, the suspension of almost every production motorcycle out there does a good job. But suspension, like all components, is built to budget and safety limits.
Honda, for example, has no wish to increase the price of a bike by fitting something that isn't necessary for the majority of customers. Likewise, they wouldn't want to fit something that, if mis-adjusted, would make the motorcycle dangerous to ride.
This means the suspension units on your bike are built to do the job satisfactorily, and no more. Mostly the only adjustment normally available on suspension units is spring pre-load, low-speed compression and low-speed rebound damping.
Adjustment of the low-speed damping circuits is what most people fiddle with in an attempt to set up their suspension.
The problem with standard adjusters comes when you're trying to be accurate. Remember the damping analogy of people trying to exit a hall through a doorway. In terms of suspension, that doorway is simply a hole that the oil is forced to pass through. Rather than opening or closing a door to restrict the flow, we simply push a needle in and out.
It's just like holding an ice-cream cone. Imagine your thumb and index finger form the hole and the ice-cream cone is the tapered needle. The further in the cone slides, the tighter it gets. It's the same idea in suspension, just more oily.
When you turn the adjuster, you're actually operating a thread. If the pitch of the thread is 2mm, then one full turn of the adjuster would move the needle in or out of the hole by 2mm. Herein is the main difference between original equipment and aftermarket damping adjusters. While it sounds good to have such a wide range of adjustment with the original equipment adjusters, you're actually better off having fine adjustment over a smaller range.
In fact, on full turn of an aftermarket adjuster might be the same as one eighth of a turn on the original equipment one. So, it's much easier to accurately dial-in the setting you require, Because manufacturers don't want you to end up with an unrideable bike, even winding the adjuster all the way in doesn't make it block off the hole completely.
Of course, that's only the low-speed side of things. Most re-valving kits also contain a new piston with a revised shim stack. This controls the high-speed compression and rebound damping.
Fitting one of these kits isn't a beginner's job in the sense that a few specialist tools make the job a lot easier. What's more, if you've never seen the inside of a set of forks, they can be difficult to understand. That said, it isn't hard once you know how.