XL 2021 Faire mieux mon code

Sub test2()
    mes_classeurs = "|isitelImmobRdV SondaNF.xlsm|isitelImmobRdVSondaNF.xlsm|isitelImmobRdV StephanieNF.xlsm|"
    Dim wbk As Workbook
    For Each wbk In Workbooks
        MsgBox wbk.Name
        If mes_classeurs Like "*|" & wbk.Name & "|*" Then
            Windows(wbk.Name).Activate
            Application.EnableEvents = True
            Application.ScreenUpdating = True
            Exit Sub
        Else
            MsgBox "LES CLASSEURS" & vbCrLf & Join(Split(mes_classeurs, "|"), vbCrLf) & vbCrLf & "SONT FERMÉS"
        End If
    Next
End Sub

Dim Message As String
Dim I As Integer


    Message = ""
    
    For I = 1 To Workbooks.Count
        With Workbooks(I)
            Select Case .Name
                   Case "isitelImmobRdV ImenNF.xlsm"
                         .Activate
                         Message = "isitelImmobRdV ImenNF.xlsm OK!"
                         Exit For
                   Case "isitelImmobRdV SondaNF.xlsm"
                         .Activate
                         Message = "isitelImmobRdV SondaNF.xlsm OK!"
                         Exit For
                   Case "isitelImmobRdV StephanieNF.xlsm"
                         .Activate
                         Message = "isitelImmobRdV StephanieNF.xlsm OK!"
                         Exit For
            End Select
        End With
    Next I
    
    If Message = "" Then
       Application.EnableEvents = True
       Application.ScreenUpdating = True
       Exit Sub
    Else
       MsgBox Message
    End If

Sub test()
'SELECTION ICHIER RDdVs
    If Not (IsOpen("isitelImmobRdV ImenNF.xlsm") And _
    IsOpen("isitelImmobRdV SondaNF.xlsm") And _
    IsOpen("isitelImmobRdV StephanieNF.xlsm")) Then MsgBox "Aucun  n'est ouvert": Exit Sub
End Sub
Function IsOpen(Classeur As String) As Boolean
Dim Wb As String
On Error Resume Next
Wb = Windows(Classeur).Caption
IsOpen = Not CBool(Err)
Err.Clear
On Error GoTo 0
End Function

Sub test2()
'SELECTION ICHIER RDdVs
  If IsOpen("isitelImmobRdV ImenNF.xlsm") Then TraitementFichier (Windows("isitelImmobRdV ImenNF.xlsm")): Exit Sub
 If IsOpen("isitelImmobRdV SondaNF.xlsm") Then TraitementFichier Windows("isitelImmobRdV SondaNF.xlsm"): Exit Sub
 If IsOpen("isitelImmobRdV StephanieNF.xlsm") Then TraitementFichier Windows("isitelImmobRdV StephanieNF.xlsm"): Exit Sub
 
End Sub
Sub TraitementFichier(Fichier As Workbook)
 'Traitement
 
End Sub

Sub Test()
Dim a, wb As Workbook, flag As Boolean
a = Array("isitelImmobRdV ImenNF.xlsm", "isitelImmobRdV SondaNF.xlsm", "isitelImmobRdV StephanieNF.xlsm")
For Each wb In Workbooks
    If IsNumeric(Application.Match(wb.Name, a, 0)) Then MsgBox "'" & wb.Name & "' est ouvert": flag = True
Next
If Not flag Then MsgBox "Aucun des 3 fichiers n'est ouvert"
End Sub

'SELECTION ICHIER RDdVs
On Error Resume Next

If Err <> 0 Then
    Windows("isitelImmobRdV ImenNF.xlsm").Activate
    MsgBox ("isitelImmobRdV ImenNF.xlsm OK!")
Else
    MsgBox "isitelImmobRdV ImenNF.xlsm n'est pas ouvert"
    Application.EnableEvents = True
    Application.ScreenUpdating = True
    Exit Sub
End If