Auto-save in VBA is reopening closed files - excel

Question

I implemented some code into a few of my excel sheets that would cause the file to autosave periodically. The issue I am running into with the code, is that when it is executed, it reopens the files that have been closed that also contain the same code.
I am looking for a way to have VBA autosave documents every so often, but it would no longer run if the file isn't open.
This is the code I have implemented:
Contained in "ThisWorkbook":
Private Sub Workbook_Open()
Application.OnTime Now + TimeValue("03:00:00"), "Save1"
End Sub
Contained in "Module 3":
Sub Save1()
Application.DisplayAlerts = False
ThisWorkbook.Save
Application.DisplayAlerts = True
Application.OnTime Now + TimeValue("03:00:00"), "Save1"
End Sub
A note: The code between all of the documents is 100% identical (except the TimeValue, which varies by a few hours among some of them).

Answer 1

Try the next approach, please:
Adapt the OnTime call to a better qualified Sub:
Private Sub Workbook_Open()
scheduleTime = Now + TimeValue("03:00:00")
Application.OnTime scheduleTime, "Module3.Save1"
End Sub
Make the Sub in discussion Private, and create a new Public variable on top of the module:
Public scheduleTime As Date
Private Sub Save1()
Application.DisplayAlerts = False
ThisWorkbook.Save
Application.DisplayAlerts = True
scheduleTime = Now + TimeValue("03:00:00")
Application.OnTime scheduleTime, "Module3.Save1"
End Sub
Clear the already set OnTime procedure:
Private Sub Workbook_BeforeClose(Cancel As Boolean)
Application.OnTime scheduleTime , "Module3.Save1", , False
End Sub
The first two items will solve the opening of other workbooks when the active workbook procedure is called. But, this should not happen and I am afraid that this is not the real opening mechanism, the workbooks are open by their own OnTime function call.
If my above supposition is True, the item 3 alone will solve the issue...

Answer 2

As you may notice, OnTime is an Application method, not a Workbook method.
This means that, even if you close the Workbook, so long as the Excel Application is still open that OnTime is still counting down. Once it hits zero, it will try to run the Subroutine - but the workbook is closed. Rather than throw an Error, Excel will reopen the Workbook, and then run the Subroutine.
In order to stop this, you will need to unscheduled the Subroutine before you close the Workbook, which will also mean Storing the time. So, you will need a Module that looks something like this:
Option Private Module
Option Explicit
Private AutoRunTime AS Date
Public Sub AutoSaveWorkbook()
ThisWorkbook.Save
AutoRunTime = Now()+TimeSerial(3,0,0) '3 hours
Application.OnTime AutoRunTime, "AutoSaveWorkbook", True
End Sub
Public Sub CancelAutoSave()
Application.OnTime AutoRunTime, "AutoSaveWorkbook", False
End Sub
Then, in the Workbook_Open even you call AutoSaveWorkbook to start things off, and in the Workbook_BeforeClose even you call CancelAutoSave to end them