VBA code runs slow

Thanks for the reply Kenneth. I am not a VBA pro by any means, I'm still learning. Your comment reminded me of an important part I omitted from original posts code. I omitted parts to try and keep it clean and not take focus away from the problem area. The part that hides and unhides sheets is controlled by an intersect. If the users enter their initials in a cell within the range it enters the date in the column next to it, and also unhides the issue sheet that goes with it.
There is also another single cell that needs to run the macro every time the value changes. Cell B4 - the user enters the number of rows they need for data and the macro unhides only the rows needed.
The problem is every time anything is entered there is about a 3 second pause before the macro finishes and you are able to enter next cell value.
I don't need to run everything when any cell is changed but at the time I started it I didn't know any better. It worked fine until I added all the sheets to unhide.

Private Sub Worksheet_Change(ByVal Target As Range)
Set rng = ActiveCell

Application.Calculation = xlCalculationManual
Application.ScreenUpdating = False

If Target.Cells.Count > 1 Then Exit Sub

        If Not Intersect(Target, Range("AD193:AD213")) Is Nothing Then
            With Target(1, -1)
                .Value = Now
            End With 

'this part hides and unhides rows on the sheet as needed by users for data entry. Rows 8-186
If Target.Address = "$B$4" Then
    Toggle_Rows
    End If

If Range("AB193") <> "" Then
        Worksheets("Issue 1").Visible = xlSheetVisible
    Else
        Worksheets("Issue 1").Visible = xlSheetHidden
    End If
    If Range("AB194") <> "" Then
        Worksheets("Issue 2").Visible = xlSheetVisible
    Else
        Worksheets("Issue 2").Visible = xlSheetHidden
    End If
    If Range("AB195") <> "" Then
        Worksheets("Issue 3").Visible = xlSheetVisible
    Else
        Worksheets("Issue 3").Visible = xlSheetHidden
    End If
    If Range("AB196") <> "" Then
        Worksheets("Issue 4").Visible = xlSheetVisible
    Else
        Worksheets("Issue 4").Visible = xlSheetHidden
    End If
    If Range("AB197") <> "" Then
        Worksheets("Issue 5").Visible = xlSheetVisible
    Else
        Worksheets("Issue 5").Visible = xlSheetHidden
    End If
    If Range("AB198") <> "" Then
        Worksheets("Issue 6").Visible = xlSheetVisible
    Else
        Worksheets("Issue 6").Visible = xlSheetHidden
    End If
    If Range("AB199") <> "" Then
        Worksheets("Issue 7").Visible = xlSheetVisible
    Else
        Worksheets("Issue 7").Visible = xlSheetHidden
    End If
    If Range("AB200") <> "" Then
        Worksheets("Issue 8").Visible = xlSheetVisible
    Else
        Worksheets("Issue 8").Visible = xlSheetHidden
    End If
    If Range("AB201") <> "" Then
        Worksheets("Issue 9").Visible = xlSheetVisible
    Else
        Worksheets("Issue 9").Visible = xlSheetHidden
    End If
    If Range("AB202") <> "" Then
        Worksheets("Issue 10").Visible = xlSheetVisible
    Else
        Worksheets("Issue 10").Visible = xlSheetHidden
    End If
    If Range("AB203") <> "" Then
        Worksheets("Issue 11").Visible = xlSheetVisible
    Else
        Worksheets("Issue 11").Visible = xlSheetHidden
    End If
    If Range("AB204") <> "" Then
        Worksheets("Issue 12").Visible = xlSheetVisible
    Else
        Worksheets("Issue 12").Visible = xlSheetHidden
    End If
    If Range("AB205") <> "" Then
        Worksheets("Issue 13").Visible = xlSheetVisible
    Else
        Worksheets("Issue 13").Visible = xlSheetHidden
    End If
    If Range("AB206") <> "" Then
        Worksheets("Issue 14").Visible = xlSheetVisible
    Else
        Worksheets("Issue 14").Visible = xlSheetHidden
    End If
    If Range("AB207") <> "" Then
        Worksheets("Issue 15").Visible = xlSheetVisible
    Else
        Worksheets("Issue 15").Visible = xlSheetHidden
    End If
    If Range("AB208") <> "" Then
        Worksheets("Issue 16").Visible = xlSheetVisible
    Else
        Worksheets("Issue 16").Visible = xlSheetHidden
    End If
     If Range("AB209") <> "" Then
        Worksheets("Issue 17").Visible = xlSheetVisible
    Else
        Worksheets("Issue 17").Visible = xlSheetHidden
    End If
    If Range("AB210") <> "" Then
        Worksheets("Issue 18").Visible = xlSheetVisible
    Else
        Worksheets("Issue 18").Visible = xlSheetHidden
    End If
    If Range("AB211") <> "" Then
        Worksheets("Issue 19").Visible = xlSheetVisible
    Else
        Worksheets("Issue 19").Visible = xlSheetHidden
    End If
    If Range("AB212") <> "" Then
        Worksheets("Issue 20").Visible = xlSheetVisible
    Else
        Worksheets("Issue 20").Visible = xlSheetHidden
    End If
    If Range("AB213") <> "" Then
        Worksheets("Issue 21").Visible = xlSheetVisible
    Else
        Worksheets("Issue 21").Visible = xlSheetHidden
    End If

Application.Calculation = xlCalculationAutomatic
Application.ScreenUpdating = True

End Sub

After your Toggle_Rows End If, you may want to try adding Application.EnableEvents=False. I like to set Application options before ON ERROR GOTO ENDNOW. I restore the options after EndNow:.

You could check the visible property value before setting. Multiple IF()s should make one consider using Select Case. Sometimes IF()s are required though.

Multiple IF()s can sometimes be reduced if one sees a pattern. In your case, one IF() is probably sufficient. The key is to use string concatenation. e.g.

Sub Ken()
  Dim Target As Range

  On Error Goto EndNow

  Set Target = Range("AD193")
  If Range("AB" & Target.Row) <> "" Then
    Worksheets("Issue " & Target.Row - 192).Visible = xlSheetVisible
  Else
    Worksheets("Issue " & Target.Row - 192).Visible = xlSheetHidden
  End If

  EndNow:
End Sub