I was interested in applying for a job here in Norway, but it turned out the company had 2-3+ interviews (which would mean spending the day at their offices) over several months, as well as some sort of IQ test and other things.

That was in the spring and they expected to have picked out some people by the end of summer.

I didn't apply, mostly because I am happy where I am, but also because a 3-5 month interview process is completely ridiculous.

The entire process just put me off from applying. If they can't talk to me once or twice and look at my resume/past projects then I do not know if I want to work there. I understand the need to find the right people, but there are limits to how many hoops I care to jump through to get the honour of working in their company.

Is this a common practice?

I can understand if you have another job and end up interviewing somewhere else while working, but if I was without a job I probably wouldn't be able to wait 5 months for someone to decide I've passed their tests.

My friend ended up applying and he was also one of the few that got hired, which is why I've heard a bit more about their process than I think I normally would.

I think using a recruiting company is more common around here. Where I work now, quite a few of us have started out working part time (as I am now) through a recruiting process, and occasionally those who work full time get picked up by our company to work directly.

My boss worked the same position I work in now, back when he was in university.