Board Thread:Wiki Discussion/@comment-1687225-20140409224752/@comment-5264386-20140410001417

Yes, I think so; just did a Google search for "Dark Souls II spell breakpoints", and found a GameFAQs thread with tables for the breakpoints of every spell. From this, it would appear that casts per slot increases at 10, 15, 26, 32, 38, 43, 49, 58, 75 and 94 Attunement. Anyway, here are the links to the tables (somewhat unfortunately, they were posted as images, so no direct copy-and-paste):
 * Hexes:http://i.imgur.com/RqWaAy5.jpg
 * Miracles: http://i.imgur.com/E4BFAbz.jpg
 * Pyromancies: http://i.imgur.com/9CnVrQS.jpg
 * Sorceries: http://i.imgur.com/dIVSOUW.jpg