Hmm, interesting. I've recently gotten back into running, however shin splints are preventing me from running as much or as far as I would like. My cardio is good, but my legs/shins are what starts screaming first forcing me to stop. I also currently run almost exclusively on a treadmill (due to winter weather), which may be a self-inflicted issue.
Do you have any insight on treadmill or track, vs. running outside?
How far do you barefoot jog each week that seems to be enough for you?
I haven't tried a treadmill. I recommend running 50-100m barefoot on solid ground like others have said and seeing how it compares / how your form changes.
I usually run 1-2 miles when I go out, not too much. Just enough to feel all the secondary leg muscles get fired up. Of course if you're new to barefoot running, people recommend starting with short distances.
On shin splints: one trigger was my poor running form. I would lunge my feet forward focusing on getting the longest stride, landing on the heel because my foot was in front of me. It didn't hurt my heel because traditional shoes are so padded there, but the physics/angles/forces of that form are bad. Instead, barefoot runners talk about "falling forward", which is exaggerated imo but gives you the cue that your feet should land under or behind your torso, not in front. This reduces the impact on the feet and legs. Barefoot running teaches this foot placement very quickly. Not sure if that's something you already do or not, but hope it helps.
EDIT - just saw your other comment. Go for a little barefoot run, maybe a few different times, and I think you'll quickly find out where your feet want to go. The "torso first, not feet first" mindset really helped me. (I'm flat footed too, and insoles didn't help me personally; not to yuck your yum, though. Maybe they'll be more comfortable for you)
Not OP, but a while back I ran weekly for months outside with no issues. It got hot, I ran two miles inside on a treadmill and got the first shin splints in my life. I hear from other runners that treadmills can hurt your form because you run differently on them than on solid ground. Try running off a treadmill and see if it helps.
I'd be curious to know whether you're heel striking when running. I'm a natural heel-striker, but I forced a change to mid-foot and my shin-splints disappeared altogether. It took a little time to build up to my heel-strike pace, but I did and was able to continue to avoid shin splints even at the same pace. All of this was done with regular running shoes (not barefoot-style).
I believe I am, but don't have great evidence to say one way or the other. I have very flat feet, and just got new orthotics/shoes actually. Any tips or helpful guides/drills on how to transition to mid-foot you would recommend?
I'd definitely be straying too far outside my wheelhouse to be comfortable with recommending how to transition, especially considering you have flat feet (I have regular arches). I can tell you that I watched this short vid and attempted to take its recommendations into account: