Ok... If I'm understanding this correctly; let's just go over the Standard Practices for windows file sharing.
Normally, seperate shares on a network device are primarily only used to restrict access to specific users. There's no reason to create 20 shares, unless you absolutely have to have 20 seperate user groups, with specific access restrictions on each.
Our devices handle access restrictions on a share-wide basis, so if a user has permission to access a share, they can access EVERY file in that share. So if you have a share, and give 10 users priveleges to it, they can all Read/Write or just Read, depending on how you set it.
For most purposes, if access restrictions is not an issue, then it's perfectly ok to have a set of subfolders in one share for data organization.
I hope that answers your question? If not, please clarify.