I think a lot of times during such interviews, they're more interested in seeing how you approach problems rather than the actual solutions that you provide (at least that's what good companies will tell you).

I haven't worked at Google but I have worked in both startups and big corporations and I find that big corporations are usually slower-paced and engineers have more 'generous timeframes' to complete features (and to do them properly).

The downside of the big company/corporation approach though is that managers tend to use the extra time to create bureaucracy around the project (in an attempt to manage risk) and this slows things down further - So while big companies tend to 'get it right the first time'; they do so at a significantly slower pace than what you would see in a startup.

What do you mean by "Google interviewing model"? Are you suggesting that this is a problem at Google and companies that interview the way it does?