I personally don’t like the type of pouch that folds out as the reload isn’t consistent and is awkward especially when reloading while moving. The 5 or 7 round is meant to hook to the front webbing of another mag pouch. This is to provide a breacher with enough slugs or buckshot to make door entry. If I was to hold more shells I’d prefer a “Shotgun Shell Dump Pouch”.
here are some pictures for reference. I also posted a pic of some shotgun shell dump pouches.