I understand your position that ideally you would receive detailed feedback to improve your performance for next interviews. Unfortunately, detailed and actionable feedback is very scarce, so don't expect a lot of actionable insights from that. Especially if did poorly during your interviews, they won't tell you a lot about it and interviewers tend to say nothing instead of saying something 'bad'.
From timing perspective, don't worry about that too much. Waiting longer than some peers might say something, but also might not say anything about the outcome. It's pure speculation. Sometimes reality is simplier than you think - sorry to say, but my Friday night dinner invite is more important to me than discussing an additional candidate's performance specifically on that same day, I can do it easily any other time fitting into my busy schedule. So really, it doesn't mean anything substantial at all.
Hope that helps - if so, please be so kind to give it a thumbs-up with the green upvote button below!