I worked for 2.5 years for a company who interviewed me for 5 hours straight. I had no warning about how long it would last, and it seemed that if I'd been struggling at any point they would have called a halt and said thanks.

That said, their interview process was all fiddly little tests, although since they were in the habit of hiring arts students and training them to code, particularly philosophers who'd done a little formal logic, they weren't about "algorithms", more just little brain teasers with simple, made up languages, and follow up questions like "could you make this any faster?"