In a 350 page book, I had to change page masters a lot when edits came in causing text to reflow. And quite often while applying the new master, a new (blank) text box would be placed underneath the text already in the document. If I caught it, I'd just delete that now extra (and empty) text box, but I know there are a lot of them just sitting there under the text boxes that contain the book's content.
A. Is there a way to find and delete all those unused text boxes?
B. Should I just leave them (They aren't causing any problems... it just seems weird / possibly a bad idea to have them sitting there...)
Well! Item A is easily addressed by a script, like the ones posted here at CreativePro. I would answer B for my own purposes by wondering if anyone (including me!) was ever going to open that INDD ever again, for another round of revisions, or conversion to epub, or really any reason whatsoever. In any case where I'd need to make further adjustments or revisions, I'd try to clean up after myself.
I don't know how to answer your question C, however. I think that's most likely a Primary Text Frame? That's all I have, if I'm right you'd go to that parent page and delete the primary text frame there, so it doesn't get reintroduced when you reapply your parent page. Just a guess, though, I'm really only here to post a link to that (really useful) empty frame management script.
Thanks! I was hoping there'd be a way to find them without going spread by spread, but I can definitely see the extra text frames in the layers panels and delete them, which is good.
As for the new/empty text boxes coming in when applying a new master, just if you're interested, I believe I've noticed it happens when I select a page and choose "apply master" from the page window's dropdown options, but not if I drag a master TO a page. Who knows why!