Using a combination of PowerShell and the "net share" command, this script shares all sub-folders within a directory, granting the Everyone group Full Control share permissions, and setting the number of simultaneous users to 20. To use this script:  Open PowerShell with elevated rights, change directory to the folder that contains the sub-folders to share, run this script.

Get-ChildItem | Where-Object { $_.PSIsContainer } | ForEach-Object { Invoke-Expression -Command ([string]::concat("net share ",$_,"=",(Get-Location).Path,"\",$_," ""/GRANT:Everyone,FULL"" ""/USERS:20"""))}