Assuming that your initial workbook has only the 20 sheets that you want to spin off to individual files, you can use this Excel macro to do the work for you.
Dim w As Worksheet
Dim wks As Worksheet
Dim b As Workbook
Const SFOLDER = "C:\Test\"
Dim sKeep As String
Dim iCount As Integer
Application.ScreenUpdating = False
For Each w In Worksheets
Set b = ActiveWorkbook
sKeep = ActiveSheet.Name
iCount = b.Worksheets.Count
On Error Resume Next
For Each wks In Worksheets
If wks.Name <> sKeep Then
.DisplayAlerts = False
.DisplayAlerts = True
On Error GoTo 0
b.SaveAs SFOLDER & b.Sheets(1).Name
Set b = Nothing
Application.ScreenUpdating = True
MsgBox "All worksheets have been saved as individual files."
/codeJust change the SFOLDER value beforehand as necessary.
(Just seen Kruncher's post - that seems a lot easier than doing this job in Monarch!)
This sounds like something that wouldn't be too tricky to crack without using Monarch at all but using Visual Basic instead. But if you'd rather not have any code lying around then you might be able to solve the problem in Monarch fine.
You mention that you don't want to do any manual work - from that, would it be right to assume that the input file will be arriving regularly, and that ideally, you just want to click on a button and create 20 files, correctly named?
Do all the sheets in the workbook have the same fields (columns)?
Assuming the file arrives each week, will all the sheets have consistent names?
If the answers to these are yes, you're in business. Create 20 projects that read in each sheet, export the unfiltered table to an Access database, appending to the existing data.
In each model, use the File() function to create a calculated field called Worksheet - complete formula Rsplit(File();2;" - ";1)
In a final project, open the complete dataset and either create 20 filters for the different values of this field, and export all filters, or use this field as a hidden key and export a summary that contains the data you need, splitting on key value changes.
Hope this helps,