It discounts what you're liable to run into once you start disassembling things on old bikes, really. Sometimes you discover that a previous owner or mechanic thought red Loctite belonged on the screws holding the four carburetors together[^0], and your afternoon now involves a torch and chasing threads in old aluminum carburetor bodies. Sometimes you find that the bike was last touched in an era before anyone knew what a JIS screwdriver was, and every fastener is nearly stripped. Sometimes it's not even the bike, but that the last supply for a part is some shop in Maine that just happened to hold one for two decades.
My last encounter with a VFR750 involved a heat gun and a pry-bar to remove the carburetors, they're no joke.
[^0]: I love my GS1000G, but this wasn't my favorite part of getting it roadworthy.