Populate cells based on criteria...

Private Sub Worksheet_Change(ByVal Target As Range)
Dim x, y, nRow, sMid1, sMid2, dayDiff As Integer
Dim sDate, eDate As Date
Dim nDate As Long

If Intersect(Target, Columns("F:F")) Is Nothing Then Exit Sub
If Target.Cells.Count > 1 Then Exit Sub
If Target.Value = vbNullString Then Exit Sub
If IsNumeric(Target.Value) = False Then Exit Sub
If Target.Value = 0 Then Exit Sub

'Do nothing when Start date = End date AND visits = 1

'Do the following when Start dat = End Date AND visits > 1
If Target.Offset(0, -2).Value = Target.Offset(0, -1).Value And Target.Value > 1 Then
    x = Target.Value
    nRow = 0
    Do
        nRow = nRow + 1
        Range(Cells(Target.Row, "A"), Cells(Target.Row, "M")).Copy
        Target.Offset(nRow, -5).PasteSpecial
        x = x - 1
    Loop Until x = 1
End If

'Determine Start date, End date and Daydiff
If Len(Target.Offset(0, -2).Value) = 8 Then sMid1 = 3 Else sMid1 = 2
If Len(Target.Offset(0, -1).Value) = 8 Then sMid2 = 3 Else sMid2 = 2

sDate = DateValue(Left(Target.Offset(0, -2).Value, Len(Target.Offset(0, -2).Value) - 6) & "-" & _
        Mid(Target.Offset(0, -2).Value, sMid1, 2) & "-" & _
        Right(Target.Offset(0, -2).Value, 4))
eDate = DateValue(Left(Target.Offset(0, -1).Value, Len(Target.Offset(0, -1).Value) - 6) & "-" & _
        Mid(Target.Offset(0, -1).Value, sMid2, 2) & "-" & _
        Right(Target.Offset(0, -1).Value, 4))

dayDiff = eDate - sDate

'Do the following when Start date <> End Date AND visits = 1
If Target.Value = 1 Then
    nRow = 0
    Do
        nRow = nRow + 1
        Range(Cells(Target.Row, "A"), Cells(Target.Row, "M")).Copy
        Target.Offset(nRow, -5).PasteSpecial
        sDate = sDate + 1
        If Month(sDate) < 10 Then
            nDate = Day(sDate) & "0" & Month(sDate) & Year(sDate)
        Else
            nDate = Day(sDate) & Month(sDate) & Year(sDate)
        End If
        Target.Offset(nRow, -5).Value = nDate
        dayDiff = dayDiff - 1
    Loop Until dayDiff = 0
End If

'Do the following when Start date <> End date AND visits > 1
x = Target.Value
nRow = 0

Do
    nRow = nRow + 1
    Range(Cells(Target.Row, "A"), Cells(Target.Row, "M")).Copy
    Target.Offset(nRow, -5).PasteSpecial
    x = x - 1
Loop Until x = 1

x = Target.Value
y = x

Do
    dayDiff = dayDiff - 1
    Range(Cells(Target.Row, "A"), Cells(Target.Row + x - 1, "M")).Copy
    Range("A" & Rows.Count).End(xlUp).Offset(1, 0).PasteSpecial
    
    sDate = sDate + 1
    If Month(sDate) < 10 Then
        nDate = Day(sDate) & "0" & Month(sDate) & Year(sDate)
    Else
        nDate = Day(sDate) & Month(sDate) & Year(sDate)
    End If
    
    For Each cell In Range(Cells(Target.Row + y, "A"), Cells(Target.Row + y + x - 1, "A"))
        cell.Value = nDate
    Next cell
    y = y + x
Loop Until dayDiff = 0

Application.CutCopyMode = False

End Sub