I use chickens as my shredders, unless you have a giant pile of leaves with just a few chickens of a breed that is not active they will have your leaves shredded in a week or 2. They also drop nitrogen pellets in the leaves as they scratch. Not an ideal situation for everyone but its works perfect for me.
(scratch grains tossed in the leaves will speed up the scratching and shredding)
Pretty much what I do too...I experimented a bit this summer with soaking whole grains mixed into the leaves...figuring whatever they don't eat will sprout and make an even more nutritious “motivation” for them to shred more leaves.
I will say that mowed leaves with bits of grass in them come with the treats already there...so either way works, and honestly, a mix is probably the best (compost ingredients of all different shapes/sizes).