Elden Ring: Shadow of the Erdtree map fragment locations—how to find each region

Trying to find your way to all of the Shadow of the Erdtree map fragments is part of the fun in Elden Ring's new expansion, but at a certain point you hold your hands up and admit "Yeah, I'm stuck with this." Though the main regions' map fragments are easy enough to find, in typical FromSoftware fashion, there are secret areas which are quite hard to reach.

That is, unless you're exploring every single nook and cranny you come across. Even then, if you missed a route the first time you explored an area...