It's more like a day or two are spent actually examining any case in general. It takes so long because a) it has to (there is an 18 month period between submission and publication) and b) there are a lot of patents and the queue is long.
Also you've asserted there is a high false positive rate, but I would put money on the fact that the rate is extremely low. Like people having a fear of flying because they see news reports about all the accidents, the realite is the chances of a patent getting through or you dying on in a plane crash are miniscule, but successful flights and genuine inventions are rarely worth writing about.