There are generally 3 rounds of interview. Mine included a recruiter screen, one-on-one with hiring manager and a technical presentation with a few managers and team members. For the 3rd round, they asked to present on a quantitative project I had done. The process lasted about 3 weeks.

I interviewed over 6 weeks. All interviews were remotely held. Four interviews. The first was with the would-be direct report. Second was with his boss. The third was a presentation of a quantitive model with four Ascend employees. The fourth was a technical question interview + normal interview with higher ups. There was a lot of miscommunication and blunders by the interviewers during the process. But these things happen when people are busy. I’ve has the same experience interviewing with Apple. It’s difficult to gives tips for the technical questions because they were remarkably simple - probably too simple. And it wasn’t clear that the interviewers were sure about what the solutions actually were. Probably no prep. From the whole process all I can say is: know basic python, know basic energy modeling, have confidence in the model you present, and hope they like your personality. There was no indication of hard skills required.