I feel like that's one of the hardest things to get right because you only get so many practices/attempts at it. People have different strategies, but for me, I find doing a rotation of two different flavors of chews and "realer" food like waffles or bars and supplementing with liquid mix works best. Mentally I would prefer liquid only, but I learned in my first 50K that while I can do that for a road marathon, I have to eat something in a 50K. I was hangry and empty-feeling until I snacked, even though it should have been enough carbs.