You've suggested revising submission material after receiving either no response or rejections from agents and I'm good with that.
However, as so many agents invite queries with pages/chapters in the submission, I'm unsure which to revise when that time comes. How to know where the "no" happened?
As for no response, if an agent is reading the query and pages/chapters, but doesn't offer a response window in the submission guidelines, is it reasonable to wait longer before closing it out?
I'm not sure when I advised revising during the query process, but I'd like to see the source, since I think this might be out of context.
I think it's out of context for just the reason you mention in paragraph two. You don't know why/when/where there's a problem. Absent concrete suggestions for revisions, you run the very real risk of revising BADLY.
By badly I mean you don't know if an agent rejected your work (or failed to respond, nowadays the more likely situation -grrrrrrrrr) for something that had nothing to do with the quality or caliber of your work.
Take a look at the Chum Bucket post from last week. Fully EIGHT of the queries were for good books but just not books right for me.
Look at the Chum Bucket results before that: it's 14 good projects.
That's a substantial portion of the queries I get, and normally those receive ONLY a form reply.
If you're not getting the results you're looking for in the query process, that's when you invest some of your hard-earned dough in an editor, or a conference. Get your pages in front of brutal, critical eyeballs.
Don't assume something is wrong with you if you're not hearing back; find out first.
As for timing, here's the definitive time table on dealing with scallywag agents who fail to reply to queries:
1. Send query.
2 A: IF agent auto-responds that query is received, wait prescribed amount of time plus 50% of prescribed time. Thus if they say they respond in 30 days, you give them 45. If they say six weeks, you give them nine.
2 B: IF agent does NOT have auto-responder, wait prescribed amount of time, then RE-SEND if no reply.
3. IF you are querying me, and you do not hear back follow 2B.
4. IF you are querying me, and you do not hear back after #3, email me or tweet to me. I respond to ALL queries that follow the general guidelines (Query Letter Diagnostics can help with that)
If you've tried twice, and not heard back, time to move on.
I find that incredibly rude and condescending in most instances, but so far I have yet to change the adoption of this course of action by many otherwise quite nice and polite agents whom I call my friends.