We just had an emergency here . . . A book (interior) designer chose Arno as the text face, and we discovered when proofing the book the string "WHQ," occurs 52 times in the text. Q-comma overprints badly.
With Arno, the kern needed for Q followed by a comma is about 200 units -- 10 units more than a nominal wordspace. For this book, we just used the large kern, but what I think is really needed is an alternate Q with a shorter or deeper tail. Swap it in (calt) when followed by a comma, semicolon, or a space -- or maybe only with a space followed by capital J, A, whatever. The calt feature is nice that way. Because the needed kern is larger than a wordspace, an alternate Q and calt feature on my short list for the Arno we use here.
If this was limited to Arno, I'd not bother to post. But it's a problem we see with a number of fonts, so maybe you'd like to consider fixes other than kerning when you draw up fonts where the Q's have substantial tails.