There's a very big difference between applying for a role at an egotistical organisation like Google, and one at a more typical software house or large enterprise.

The majority of roles, in my experience, have a quick (one hour or so) task to do beforehand, like prepare a presentation on infrastructure, or solve a code problem at home and then a one to one and a half hour interview with the hiring manager, HR, and someone else. In these situations there isn't a whole lot to prepare for in my opinion. Know the shit you're applying for, know the basics about the company (and try to guage their culture from Glassdoor etc, or when you step through the door), and go from there.

If someone was making me spend days travelling to/from multiple interviews, do hours long homework, or trying to catch me out with code I'd walk away. It speaks volumes about their respect for you.