This was specific to my team, but I only had 3 short calls, 1 being the offer. Get a good referral and you'll be set up well. Other interns were required to answer some technical questions about C++ or python. C++ if iTero teams or Python and C++ for R&D. Really depends on what team you're working with. The people at Align are awesome. No full time offer due to company circumstances but would return if I could just because the of the people.