In my opinion, it would be logical for the appearance of an indicator of comments for the indicator of comments to appear (the number of comments appearing in the Habr topic after my last post).
Here, for example, as shown in the picture (35 total, 13 + 13 new)
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The fact is that it is easy to monitor 1-2 topics at once, but 15-20 is much more difficult, and mail notifications (about the response to the Habr-post) come a little late (because of the queue for the distribution).