Change length of For loop while in the loop

Question

I have a bunch of code that goes through a set of data and then finds the row where the data goes to the next value step (5 unit increments). When this location is found, 5 rows are inserted and in those rows, the STDEVP, MIN, MAX, and AVERAGE are calculated over the range of that block of data. After this is entered, the loop continues to go through the data until it hits the last row (lastRow variable). The code for this is shown below:

Sub sectionBlocking()
Dim lastRow As Integer
Dim lastColumn As Integer
Dim sectionLastRow As Integer
Dim initialValue As Double
Dim cellDifference As Double
Dim stepSize As Integer
Dim firstCell As Integer
Dim lastCell As Integer
firstCell = 2
lastCell = 2
initialValue = 84
stepSize = 5
lastRow = Range("A1").End(xlDown).Row
lastColumn = Range("A1").End(xlToRight).Column
For x = 2 To lastRow
    cellDifference = Range("B" & (x)).Value - initialValue
    If Abs(cellDifference) > 1 Then
        lastCell = x - 1
        Range("B" & (x)).EntireRow.Insert
        Range("A" & (x)) = "StdDev"
        For y = 2 To lastColumn
            Cells(x, y).FormulaR1C1 = "=STDEVP(" & "R" & firstCell & "C" & y & ": R" & lastCell & "C" & y & ")"
        Next y
        x = x + 1
        Range("B" & (x)).EntireRow.Insert
        Range("A" & (x)) = "MIN"
        For y = 2 To lastColumn
            Cells(x, y).FormulaR1C1 = "=MIN(" & "R" & firstCell & "C" & y & ": R" & lastCell & "C" & y & ")"
        Next y
        x = x + 1
        Range("B" & (x)).EntireRow.Insert
        Range("A" & (x)) = "MAX"
        For y = 2 To lastColumn
            Cells(x, y).FormulaR1C1 = "=MAX(" & "R" & firstCell & "C" & y & ": R" & lastCell & "C" & y & ")"
        Next y
        x = x + 1
        Range("B" & (x)).EntireRow.Insert
        Range("A" & (x)) = "AVG"
        For y = 2 To lastColumn
            Cells(x, y).FormulaR1C1 = "=AVERAGE(" & "R" & firstCell & "C" & y & ": R" & lastCell & "C" & y & ")"
        Next y
        x = x + 1
        Range("B" & (x)).EntireRow.Insert
        x = x + 1
        firstCell = x
        initialValue = initialValue + stepSize
        'lastRow = lastRow + 5
    End If
Next x
lastCell = x - 1
Range("B" & (x)).EntireRow.Insert
Range("A" & (x)) = "StdDev"
For y = 2 To lastColumn
    Cells(x, y).FormulaR1C1 = "=STDEVP(" & "R" & firstCell & "C" & y & ": R" & lastCell & "C" & y & ")"
Next y
x = x + 1
Range("B" & (x)).EntireRow.Insert
Range("A" & (x)) = "MIN"
For y = 2 To lastColumn
    Cells(x, y).FormulaR1C1 = "=MIN(" & "R" & firstCell & "C" & y & ": R" & lastCell & "C" & y & ")"
Next y
x = x + 1
Range("B" & (x)).EntireRow.Insert
Range("A" & (x)) = "MAX"
For y = 2 To lastColumn
    Cells(x, y).FormulaR1C1 = "=MAX(" & "R" & firstCell & "C" & y & ": R" & lastCell & "C" & y & ")"
Next y
x = x + 1
Range("B" & (x)).EntireRow.Insert
Range("A" & (x)) = "AVG"
For y = 2 To lastColumn
    Cells(x, y).FormulaR1C1 = "=AVERAGE(" & "R" & firstCell & "C" & y & ": R" & lastCell & "C" & y & ")"
Next y
'lastRow = lastRow + 4
End Sub

This worked perfectly until I tried to execute the last 24 lines of code only to find that the macro had inserted the new lines in the middle of the last block of data instead of the end, as intended. I went through the debugging and realized that the row value variable "x" in the For loop was stopping at the original "lastRow" location and not the new location after the new rows had been input into the chart. This led me to try and put in the line of code below (commented above to show my progress in debugging myself):

lastRow = lastRow + 5

This was put inside the For loop to have the "lastRow" value increase by the number of rows that were added, every time rows were added. Unfortunately, this did not work either. The "lastRow" variable was increasing its value (as found through stepping through the macro), but the For loop still ended at the same spot as without that line.

My TL;DR version of the questions is: Is there a way to increase the length of the For loop while you are already inside the loop itself or is there a more elegant way to perform this same operation?

I can provide some of the data if the explanation is confusing. Thank you for your time.

Answer 1

I did a simple test and found the same problem:

Sub Macro1()
    Dim x As Integer: x = 10

    For i = 1 To x
        If (i = 5) Then
            x = 15
        End If
    Next

    MsgBox (i)
End Sub

Looks like excel does precompile the limit of a for loop. You can change your loop to a while instead.

See this post

x = 2

While x <= lastRow
    cellDifference = Range("B" & (x)).Value - initialValue
    If Abs(cellDifference) > 1 Then
        'your code

        lastRow = lastRow + 1
    End If
    x = x + 1
Wend

Answer 2

I would try a Do_While_Loop

Do While x <= lastRow
    'Code that triggers insert
    lastRow = lastRow + 5
    '.....
    x = x + 1
Loop