It is called "limited objectives". The fact is they were fighting in friendly territory while the Georgian military was trying to hold onto territory populated by people who wanted them to leave. It's not rocket science. Russia hardly had to disturb its military capability to toss the hated Georgians out. Now, suppose Russia for some demented idea wanted to annex Georgia. THEN you'd start to see how long a war can stretch out. Compare Israel in Sinai versus Israel in Lebanon. Same kinda deal.

You mean like Chechneya? It requires being brutal and dirty. But Russia can deliver brutal in a way the west can't without it being all over the news.