The very fact that "preparing for 8 months for a Google interview" is a thing highlights all the things that have gone wrong at Google and their widely panned bad recruitment practices.

The process has become about recruiting people that are good at the silly process and not about recruiting the best people. Probably OK if Google is in 'megacorp looking to feed more skillled cogs into the machine' mode (which it mostly is), but unlikely the process finds the person that builds the next Google.