Actually, I did one of these jumping from one megacorp to another. It took up my entire weekend, but I landed the interview. I then had to take 2 days off to fly out for the interview. Luckily, I got the job.
The process was much the same as you described: multiple day test followed by taking two days off to fly out for the interview. Except I didn't get the job and nobody who interviewed me ever looked at the take home test.