Has anyone done formation and is it worth it?

Definitely good questions. We stand by what we do but we also don't do everything and I fully support making sure you know what we do and know it's a good decision for you. Overall I would say we are good for half of what you mentioned. The SD and technical behavioral practice the explanation part. Technical behavioral is about talking about your past work in the best way possible. SD is about connecting your big scale experience with more general concepts and applying those as tools to discussing general systems problems. Anyone can read a solid systems design book for general materials and we're focused on actually applying the tools and communicating well in group and interview settings (and getting feedback) so you can successfully pass system design interviews. We don't do any hands on projects or capstone projects and we don't do anything that builds your resume. It's something on the radar for helping people with less experience, but for most of the top tier jobs they just want to see really world work experience + good full stack interview performance. Now regarding specific technology questions, two buckets: 1. Trying to see how much experience you have with big scale systems but they don't actually care about specific technologies, just want to see you have experience on systems at the scale where you need to solve those kinds of problems, like building a massive data pipeline. We help for this. 2. Looking for experience with specific technologies because they want you to show up day one able to use those tools and do work. We DON'T help for this. Real work experience with a tool is what they are looking for and you have it or you don't. Some programs help you fake it to try to get by interview and we do not do that. So our engineers and product people are building our platform, which is a product, they aren't mentoring for the most part. There is one team member who has 20 years of experience and actually does lead the mentorship side in terms of content, configuration, and he's a special person that is also one of the best teachers in the world at this. The mentors who run sessions are industry engineers who vary from more like great teachers to just great engineers who are not good teachers... it's a mix and you work with all kinds of mentors and give feedback on who you like and don't. We often find one person will hate a mentor and another person loves them, so over time you'll find the mentors that work for your style and spend more time in their sessions. Pulling off the scheduling and feedback parts of this system are very hard problems and why we have those strong engineers building the underlying technology.