Sorry ... I just can't stand it any more.
If rs!Stop_date < rs2!weekendings - 4 Then rs1!Mon = away and rs1!Mon = away
This is a very poorly written statement.
To have multiple statements on a line, you must separate them using a colon
If rs!Stop_date < rs2!weekendings - 4 Then rs1!Mon = away
: rs1!Mon = away
This still will not update fields "Mon" and "Tue". You cannot change the value of a field in a recordset without using "rs1.Edit" & "rs1.Update". 
There are two forms of the IF() function: the single line and the block form.
The single line form has been depreciated: it was used back in the day when memory was expensive, processors were slow and you had to count bytes and cycles.
In VBA you should always use the block form; there is no reason not to. The block form is much easier to read.
This is the block form:
Code:
Away = 0
If rs!Stop_date < rs2!weekendings - 4 Then
rs1.Edit
rs1!Mon = Away
rs1!Tue = Away
rs1.Update
End If
OK, off my rant.
Having said all of that, the single line will work if you use this:
Code:
If rs!Stop_date < rs2!weekendings - 4 Then rs1.Edit: rs1!Mon = Away: rs1!Tue = Away: rs1.Update
Note the colons in the line.
As I said, not as easy to read/understand.......