I was surprised in the lack of scalability of the Google process given it's breadth. Basically an employee screen (moderate), six onsite one-on-ones (tough). No doubt, each question area is relevant, but I'd be hard pressed to agree that prepping for weeks for this breadth translates well to success in the role. There is no fail fast, pivot, consult, in this process, which is more real-life success. I'd recommend segmenting into two separate onsites with a reduced scope. I think you'd be surprised how much better people would do when looking at the total package.
I'd also say to the interviewer, stop leading the interviews and start listening more you may be surprised by a unique approach. You need to be exceptional as a candidate in the process, but if you offer no patience and can't back off your own expected result, you can't expect to be impressed. Enough said. Another un-google.
Overall, I believe success on the Google interview is more about luck of the draw with interviewer openness and candidate assertiveness on your ideas. Surprising and not what I expected.