Great response, not sure what I've done this time to rattle your cage? It was asked further up how much people are paying...
If you go in and ask for some specific settings and they have the kit to measure it, then 9/10 times I've got what I asked for. I used the same garage in Swindon for years while I was living there and they were always within an acceptable margin of what I asked for without spending half a day doing it.
If you want utter perfection then it will take most of a day as everything moves around but getting to within 5-10% or so adjusting almost everything will take an hour tops. The last little bit isn't worth the ludicrous amount of time it takes for a road car or even most track cars.
Most of the independent garages which have the laser kit will know how things respond when changing something else. The likes of Kwik Fit are mugs and will most likely fob you off or just dick about with it until it's somewhere near factory, but if you avoid most of the chain places they are pretty good in my experience.