Skip online assessments and do on-site possible ?

I'm a senior dev and I got contacted by an amazon recruiter and the process is to do an online assessment first, then a real phone test with a human being and then an onsite interview. Is this normal?

I'm a senior dev and I got contacted by an amazon recruiter and the process is to do an online assessment first, then a real phone test with a human being and then an onsite interview. Is this normal? Is they anyway to skip the online assessment as I have to study a lot before I call myself ready to do these algorithm online quizzes? What if I contact my previous colleagues who work at amazon and ask for referral? Pretty sure I will fail even if I study as I haven't applied to big companies in a few years and I have to take it within a week. Last time I did both Microsoft and LinkedIn interviews and both already talked to a real person aka phone screen first. Should I reject it? Can I just skip to in person interview? Thanks