I tend to learn application horizontally: instead of going deep into one application such as Blender and later moving to the next, I focus on features and the differences between programs.
It’s like Comparative Languages (human or computer).
The question is about the location of JPG, PNG and similar files.
Maya: folder named “sourceimages”
Cinema 4D: folder named “tex”
3ds Max: not enforced, users tend to place them in a folder named “Textures”.
What is the equivalent in Blender?
Blender (again) is one of these 3D applications doing it differently.
When saving a .blend file in a folder, Blender will create some subfolders for you, one of them is a Textures folder.
But when you want to work with your own folder setup, you can set a folder in the Preferences>File Paths>Textures folder. By default it is set to //, which means it will look on the local folder level.
What would benefit users is a project manager like in Maya, Houdini and Softimage. One click folder/subfolder setup. Especially when working on a project with multiple people, proper folders strcutures and rules will benefit greatly.
Oh… And the Preference path is global, so switching projects will need a relink to the proper folder.