I had 6 interviews that went relatively well, and then waited 3 months... During that time, the recruiters never contacted spontaneously to keep me in the loop and when I contacted them, either I was told to wait or didn't get any reply at all. I got the final feedback in the end (3 months after my 6th interview) because I tracked down the hiring manager on social media and asked politely for an update. I did receive a constructive feedback but gosh it was difficult to get it! It turns out the position had been cancelled weeks ago and that wanted to call me but didn't find the time. I understand you are busy but it's important to treat your candidates with respect. Think about your employer branding as well