Matthew raised an interesting point the other day on VP, after someone mentioned the Castalia comics lines were experimenting with folios. The question was whether this was a good idea or a bad one. I'm firmly in the pro camp. Having wanted to comment on specific panels while reviewing some of the early Arkhaven issues, and having found it somewhat irritating to have to type things like "the top left panel opposite the full page splash of Rebel where the guy in the mask is crashing through the skylight", I can definitely say replacing that with "top left panel page 22" would be preferable.
My own theory, as a former retailer, was that many comics publishers dropped the folios to avoid drawing attention to the increasing number of full page ads they've sold over the years. And in fact, this article confirms that's part of the reason folios are out of vogue:
https://pencilpanelpage.wordpress.com/2 ... in-comics/
With Arkhaven not currently selling ads in the body of the comic, that's a non-issue. I think as long as the folios are unobtrusive, they're definitely useful.