Periodic ScreenUpdates

I appreciate the help. I have a loop routine in a large spreadsheet that takes a while to run. Mostly due to the size of the worksheet itself but I'm looking for ways to speed it up, like turning the screenupdating = false. However due to the length of the routine (taking anywhere from 15-30mins), I wanted to create a periodic screenupdate. I've placed it inside an If statement nestled in a loop but its not engaging and I don't know why. I should add that if I add a simple msgbox w/ the screenupdate, it'll work as intended.

Thank you for anyone's time put into trying to help me here.

Sub ScreenUpdate()
Dim i as integer

Application.ScreenUpdating = False
N=10
Do While i < 300

  < Normal Code Routine >

    IterationCount = i

    If IterationCount Mod N = 0 Then
        Application.ScreenUpdating = True
    Else
    End If
    
    Application.ScreenUpdating = False

    i=i+1
Loop

Application.ScreenUpdating = True

End Sub

Carim. I understand the 30minute macro is unusual but its not the macro's fault. Its essentially a range of goal seeks and is as simple as macros get. What makes it take so long is the amount of formulas behind the GS iterations (as well as the overall size of the spreadsheet).

I just thought a screenupdating could shave a few minutes off and would be a simple add.

Here is is JkBox. I appreciate your your time on this.

Sub Goal_Seek_Start_Element()

Dim i As Integer, Last As Integer
i = 7   'starting row
N = 2 
Last = Range("C2") + i
Application.ScreenUpdating = False

Do While i <= Last - 1
    'Starting Guess
        Range("D" & i) = Range("AA" & i)
    
    Range("E" & i).GoalSeek Goal:=0, ChangingCell:=Range("D" & i)
    

    IterationCount = i - 6
    
    If IterationCount Mod N = 0 Then
        DoEvents
        Application.ScreenUpdating = True
    Else
    End If
    
    Application.ScreenUpdating = False
    
    
    i = i + 1
Loop

Application.ScreenUpdating = True

End Sub