SAFD: Thankfully my stomach has been pretty tolerant of most fuel, even on long runs and marathons. I usually run in the afternoon, so I'm sure to eat a decent breakfast (during the week, oatmeal and berries; weekends often eggs with spinach) and something small about 15-30 minutes before a run (applesauce pouch most often).
I'll fuel for any run an hour or more. I used to use Tailwind, but got tired of having to deal with liquids all the time. I was also not great at estimating how much I needed, so I often ended up with some sloshing and a LOT of bathroom stops (sorry for that
@Herding_Cats). I started randomly adding in waffles but again, not really paying attention to much aside from how I felt.
A few years ago we moved to Vermont and I came across Untapped as it is produced very close to me. I liked that it was so simple, so I switched entirely to their products. For less than two hours, I'll just use the "gels" and alternate between salted raspberry and classic or mint. Two hours or more and I add in a waffle. I fuel every 25 minutes and take sips of water as I feel like it, then after every workout I have something with pretty high protein within about 30 minutes and a recovery or electrolyte drink.
Now that I'm starting to dial in my training for Chicago, I'm paying more attention to what I need and my coach is helping me to calculate and test that. I've probably been taking too many carbs and not enough salt or liquid. So I just ordered a mix of products from Maurten, LMNT, Skratch and Precision to try from The Feed. Paying close attention to all these responses!
Side note: I'm also now deep down the rabbit hole of researching hydration belts and (maybe) vests. I do most of my runs on a treadmill, but tried an outdoor run this weekend and actually enjoyed it -- despite all the hills in my area and the bouncy (NOT running) vest that I decided to stuff all my things into. Mixing some of these hilly runs in will definitely help me figure out what will work for me on the course in Chicago. At Disney I rely entirely on what rD provides for hydration, but I don't want to have to do that. I'm leaning toward belts because I get hot easily and Chicago doesn't allow vests with back bladders (but you can have bottles in the front pockets).