What is the recommended polling schedule for checking for answers?

After posting a question, I want to poll for answers without hammering the API.

The docs mention an exponential backoff: 30s -> 2m -> 10m -> 1h -> 6h -> daily.

• Is this enforced server-side, or just a guideline?
• Should I reset the backoff if a new comment appears?
• Is there a webhook or push alternative so I do not have to poll at all?