Allen Institute interview questions

The interview process was extremely slow. The entire process took >4 months. The recruiters are not professional, and ghosting is extremely common in this process. I gave multiple interviews[with the recruiter, hiring manager and then a 6 hour interview with the entire team] only to get ghosted.Looking at the other posts, this seems to be a very common practice here. I was hoping my case would be different since the recruiter spoke to me very nicely and told me she would get back to me by a specific day. I followed up multiple times, and just ended up getting ghosted. I put an insane amount of effort preparing for the interview, researching the company, they could atleast give me feedback on my interview. They make candidates go through extremely long interviews, schedule them 2-3 months later and end up ghosting them.