Got a response yesterday from an agent. One of the scores I had queried in my search.
It was the usual, "Pardon this form response but we get so many that if we're going to reply in a timely manner ... blah blah blah ... doesn't fit our needs ... blah blah blah ... perhaps another agent ... etc."
I looked it up in the list I kept of every agent queried and their response. Wow. Turns out I queried this agency last June, eight months ago. I'd hate to think how long a reply would have taken if they hadn't used the form response! And that was an agency that didn't request any pages so it's not like they had a long manuscript to wade through. Just the query, which I kept under 400 words.
I thanked them for their reply and said indeed, another agent had signed me, six months ago. No reason to be any cattier than that. Karma, don't you know.
But for future reference, if more than, say, four months have gone by, you can safely delete it and move on. Because I sure did.