It all depends on company SOP's.
I'll explain my companies SOP as they all differ. Initial walkaround is to be done as outlined in the Aircraft Operating Manual, such as checking all important parts thouroughly and looking in the compressor and turbine blades for cracks knicks or anything unusual. In the landing gear bays etc.
After that check every check can be done by a fast walk around only looking at specific points that could be damaged while in flight ( Compressors, Pitot, Static, Wheels, etc. and can be done with in 2 min.
Everyone doesn't differently, but the main goal should be as outlined in your SOP's!