The standard procedure involves a few interviews before a panel interview (HR, manager(s), coding, panel). However, there was no homogeneity in the difficulty of these interviews.

I haven't had an experience thus far where there was such a discrepancy between the first few interviews and the final round. The difference was so significant that it makes me wonder what Lucid has in mind when its technical interviews go from quite basic in one stage to suddenly much more difficult.

I would think you'd look to have a more consistent effort in testing a potential applicant before offering them a final interview, but alas, I am not a recruiter nor am I a hiring manager.

It didn't seem to me as though all the engineers involved in the whole process understood my level of experience (recent college grad) and what I was expected to bring to the table. Consequently, the types of questions to prepare before the interviews were unclear.

Under NDA, but can expect questions related to OS and HALs. Also expect questions on basic concepts, such as understanding how a loop works.