I just had my extended done last night. It just leaves the landing strip at my request, everything else done, inlcuding backside and so on.
I think it really depends what you want when you go and which salon.
The one I use is great, very clean and hygenic, usually ask if I want to wear the cottong g string thing, which I decline.
They also ask how far I go as in do I want my backside and everything done.