Switching every 2-3 years? Sounds about right. The only time I've stuck around longer was if there was a really good reason (like an RSU vesting schedule). It seems as though most companies will prioritise getting new people in rather than retention of existing staff. The other issue I've seen is that sometimes people who stick around at the same company for a while get a bit institutionalised and have difficulties switching to another company. Where I'm currently working in all hands meetings there's usually a work anniversary section and some people have been at the company for over 30 years. I just couldn't imagine that.

My last few jobs have only lasted 6 months though. One of them lied to me in the interview and when I started it turned out I was doing nothing but dealing with legacy systems. Another had some interesting problems which meant I had 3 managers in 6 months. Then I got an intern who couldn't program because he was related to one of the senior guys in the office.

Anyway, in terms of interviewing, personally I tend to just prep a few months before I start looking. Just do a load of leetcode, read up on some system design crap, that kind of thing. It all feels like a bit of a farce to be honest because everyone asks the same questions and by now everyone knows what will be asked and what the standard answers are. It's just a case of being able to memorise the standard answers.