It used to be that when you had multiple consecutive comments on the same post, they appeared in a single entry in your inbox.
42 comments on The future of meta.stackoverflow and meta.stackexchange
I don't know when this changed, but now every comment is its separate entry.
Thus, if you happen to participate in a high-profile thread (shudder reply to Jeff on MSO shudder, your inbox is shot for a while.
Please bring back the former behavior of grouping consecutive comments on the same post, and answers on the same question.