<Flags()>
Public Enum WT As Integer
    Mo = 1       '0. Bit
    Di = 2       '1 .Bit
    Mi = 4       '2. Bit
    [Do] = 8     '3. Bit
    Fr = 16      '4. Bit
    Sa = 32      '5. Bit
    So = 64      '6. Bit
End Enum
 
Public Function Datumschleife(ByVal DateStart As Date, ByVal DateEnd As Date, _
  Optional ByVal WTage As Integer = 127) As List(Of Dat
 
    ' Anzahl Tage zwischen Datum1 und Datum2 ermitteln
    Dim Days As Integer = DateEnd.Subtract(DateStart).Days + 1
    Datumschleife = New List(Of Date)
 
    For i As Integer = 0 To Days - 1
 
        ' Prüfen, ob ermittelter Wochentag berücksichtigt werden soll
        Select Case True
            Case DateStart.AddDays(i).DayOfWeek = DayOfWeek.Monday AndAlso _
              CBool(WTage And (1 << 0))
                Datumschleife.Add(DateStart.AddDays(i))
            Case DateStart.AddDays(i).DayOfWeek = DayOfWeek.Tuesday AndAlso _
              CBool(WTage And (1 << 1))
                Datumschleife.Add(DateStart.AddDays(i))
            Case DateStart.AddDays(i).DayOfWeek = DayOfWeek.Wednesday AndAlso _
              CBool(WTage And (1 << 2))
                Datumschleife.Add(DateStart.AddDays(i))
            Case DateStart.AddDays(i).DayOfWeek = DayOfWeek.Thursday AndAlso _
              CBool(WTage And (1 << 3))
                Datumschleife.Add(DateStart.AddDays(i))
            Case DateStart.AddDays(i).DayOfWeek = DayOfWeek.Friday AndAlso _
              CBool(WTage And (1 << 4))
                Datumschleife.Add(DateStart.AddDays(i))
            Case DateStart.AddDays(i).DayOfWeek = DayOfWeek.Saturday AndAlso _
              CBool(WTage And (1 << 5))
                Datumschleife.Add(DateStart.AddDays(i))
            Case DateStart.AddDays(i).DayOfWeek = DayOfWeek.Sunday AndAlso _
              CBool(WTage And (1 << 6))
                Datumschleife.Add(DateStart.AddDays(i))
        End Select
    Next
 
    Return Datumschleife
 
End Function

Dim wts As Integer = WT.Mo Or WT.Di Or WT.Mi Or WT.Do Or WT.Fr
Dim l As List(Of Date) = Datumschleife(New Date(2020, 1, 1), Date.Today, wts)
For Each d As Date In l
    ListView1.Items.Add(d.ToLongDateString)
Next