I had the negative and worst experience interviewing for the role of Data Scientist with McKinsey Quantum Black. They took 6 rounds and didn't care to provide any constructive feedback. The HRs usually don't care to respond. Throughout the process, they didn't answer the emails nor to my calls. The process was time consuming and took around 2.5 months. After every round, there was usually a gap of 12-14 days taken by HR to respond. Rest regarding the interview process, there were 6 rounds in total. All the interviewers were calm and humble. The first round centered around classical machine learning and my project. Second, round focused on coding skills on hacker earth. The third round focused on Gen AI concepts. The fourth round was with a senior member where he asked about the project and Gen AI. The fifth and sixth round was in the office in person with the director which focused on project and general ML concepts. After the last round, no one cared to reach out or provide any feedback on the process. I dropped multiple mails and calls but no response. After 2-3 weeks, I tried for the last time to call the recruiter, fortunately she picked up the call and just said we are not proceeding ahead with your candidature and as a feedback she mentioned that your technical expertise is good but we take the feedback in amalgamation from all the interviewers and then decide the result which was contradicting statement as if the candidate didn't performed good then why take 6 rounds and waste his/her time. On the same day, after sometime, the HR dropped an email stating that they are not proceeding ahead in process. The candidate has gone through 6 rounds, at least he has the right to know the constructive feedback. At last, I would say be prepared and think again before getting involved within the interview process with this company.