It very much depends on what you happen to get on the system. I tend to go with whatever seems like it'd take less time - very often, the steps described (or thereabouts) will result in a malware-free system in less time than it'd take for Windows updates after reinstalling. So they're worth a shot.
If the malware just won't go away though, then sure, it's more efficient to just reformat/etc than spend days fighting with it.