Final Round Interview Timeline- should I be worried?

Here’s the timeline:

* Round 1: I advanced
* Round 2: I advanced to the next round.
* Round 3: I advanced again.
* Final round: waiting

After each of my first three rounds, I heard back within approximately 3–6 days. It’s now been 8 days since my third-round interview, and I haven’t received an update.

1. When should I follow up with them?
2. Is it normal to take longer to respond after a third-round interview when the final round is a scheduled, in-person event?
3. Would they typically finish interviewing all candidates before deciding, or might they extend invitations on a rolling basis?
4. If a candidate clearly isn’t moving forward, would they typically be rejected quickly, or might they wait until the final-round shortlist is confirmed?
5. Does a personal response to my thank-you email mean anything, or should I not read into it?

I’d especially appreciate hearing from anyone who has been through a similar process. Thanks!