Not many guys will go through the steps/pain to get that kind of results. You see that it's hard work. But, what most guys don't realize is that, even if you neglect them for quite a while after getting them to the point in my pics, they'll stay like that for a fairly long time. The finer the surface is, the better it is for self protection. Now, that's not a good practice though, so, a touch up, like stated, should be about every 2-3 months, depending on operating conditions. Some Mothers or, what ever aluminum polish you can find will do a good touch up, about 10-15 minutes per side of each wheel.
"Semi-Chrome" aluminum paste/polish is great for that touch up, once their in prime, polished condition.