I recently switched jobs and got interviews in 5 big companies for mid/senior Software Engineering positions. All their processes were fairly similar: Two coding interviews, one system design interview and a conversation with the hiring manager. I might be biased because this process was beneficial for me, but here are my 2 cents on it:

It's easier to get a position in a stack you don't have professional experience with. You're tested for your ability to learn CS concepts, not stack specific knowledge. All 5 positions I interviewed to had different technologies. If I had to learn the specifics of each before applying, I would likely not get offered any positions.