Which requests do I not respond to?

BM has a request:

TC,

would you take a hand few requests (maybe 10 or so) from the comments here and tell us (in a word:'NO' or a short sentence why) you will NOT fill them?

I hope this request is excluded from your picks!

I won't handle those I have already written about and have no new insight on, those I will soon write about (I prefer for most of my non-blog writing to be relatively fresh), and those I have nothing to say about at all, usually because of my own lack of knowledge.  On top of that big pile, a small number of requests — small in percentage terms at least — strike me as best addressed by a quizzical, offbeat non-response.

I answer all the rest.