My gf interviewed at google from 8am to 2:30pm (after 2 half-hour to hour-long phone screens).
Northrop Grumman had a (wasteful) 8 hour "college day" that was an hour of technical interviews, 4 hours of propaganda, and 2 hours of arbitrary fluff like team building games among the applicants.
The ~5 or so on-sites I've had apart from NG were 2-4 hours.
Told the last Google recruiter that contacted me "No, I've been through your interview process once years ago, I'm not subjecting myself to that again."
I got my current job after a brief phone screen and a one hour in-person interview. It came with a big pay increase and the smartest people I've worked with so far.
I'm not sure why so many companies insist on the days-long torture interviews (I've been through several), but I know they're not necessary to find good people.
Northrop Grumman had a (wasteful) 8 hour "college day" that was an hour of technical interviews, 4 hours of propaganda, and 2 hours of arbitrary fluff like team building games among the applicants.
The ~5 or so on-sites I've had apart from NG were 2-4 hours.