I'll give my side, although wait on others inputs of course before reaching a good conflusion.
For organization in Xperience by Kentico, you have a couple things:
- Channels (IE Web Channel) - This is mainly an organizational unit for different websites, or channels, so i wouldn't use this as a primary organizational unit, but all Web Pages go in here
- Content Hub Workspaces - Each workspace can have different permissions and/or be used for different purposes. There isn't necessarily a limit on WHAT you can put in each workspace, just WHO can put certain things. You largely don't use these for APIs.
- Content Hub Folders - Hierarchy structure of folders that house content items. These do not impact retrieval of content items, and you cannot set roles on them. They are purely a way to organize Content Items. When you click on a folder, it only shows you the content items IN the folder (not underneath) currently, so keep that in mind.
- Content Hub Smart Folders - These are programmatically defined folders that 'group' content items that match the filters or programmatic features. This is largely used in API retrieval, sometimes for organization.
I personally LOVE Workspaces and Folders, I have many workspaces for different type of things (for Physics Classroom, I have a workspace for each type of interactive we offer, as well as a workspace for media files, one for misc site related content, etc). However, I'm also the only one managing content, and i'm meticulous about putting things in a proper folder. When you create a new content item, by default, it will just throw it in the root of your workspace, and the UI currently doesn't remember your "Last" position, which hopefully they fix at some point. This means that the 'root' folder eventually gets cluttered, but that doesn't really matter in terms of performance or anything, and when you search for a content item, the root folder shows ALL items in all folders anyway, so no big deal.
I would not use the Channel (Web Pages) for anything but ACTUAL web pages - with the exception of anything that also needs the page builder (as only Web Pages are page builder enabled). This is more rare, but it is possible to re-use page builder sections using one of my modules (Partial Widget Page).
Reusable schemas are mainly used for common-item things (like meta data) that span across content types. It's nice because if our item uses a reusable schema, in code your MyItem is also of type MyReusableContent so you can type check and cast it easily.
Overall, with how well the API works now, balance out the time it takes to add individual elements (which isn't too hard with the new UI side bar for creating sub content) and making things too 'bulky'. Xperience does the rest. I went for more modular and smaller pieces, but i also had very structured data and i created my own imports to organized it well.