Option Explicit
Sub FürJedesArbeitsblatt()
Dim wks As Excel.Worksheet
Dim rng As Excel.Range
For Each wks In ThisWorkbook.Worksheets
With wks
Call WerteErsetzen(.Range("C2:Z366"))
End With
Next wks
End Sub
Sub WerteErsetzen(ByRef rng As Excel.Range)
Dim vArr As Variant
Dim i As Long, ii As Long
i = 1
ii = 1
vArr = rng
For i = LBound(vArr, 1) To UBound(vArr, 1) Step 1
For ii = LBound(vArr, 2) To UBound(vArr, 2) Step 1
vArr(i, ii) = IIf((vArr(i, ii) > 20), 1, 0)
Next ii
Next i
rng.Resize(UBound(vArr, 1), UBound(vArr, 2)).Value = vArr
End Sub