I had 4 rounds on the same day, and the last one felt clueless – I didn't understand why I was speaking to that person.

Still, there is no update from their side, even after continuous follow-ups through email. The HR department doesn't pick up calls at all.

HR needs to learn to respect candidates' time, as we take time off to attend these interviews. They should have the courtesy to respond with feedback, even if it's negative. It has been almost a month now, and I don't have any hopes.

Can anyone tell me how long HR usually takes to respond?

To walk through my resume.