I was asking if the 3 for the group interval was always 3 or if it needed to be calculated from the source data or from perhaps a cell value in the sheet. As it is I've used a hard-coded 3.

In my code, both the starting value and the group pitch are manually entered. Specifically, enter the group spacing in cell B8, and enter the starting data value in cell C1. A judgment condition is also set. When cells C1 and C2 have data and cell B8 has no input data, the group distance can be obtained by subtracting the value of cell C1 from the value of cell C2. Then automatically generate all the separation points of the data, and then other data.

These logics are reflected in my following code:
p = ActiveSheet.Cells.Rows.Count
q = ActiveSheet.Cells(p, 3).End(xlUp).Row
If q >= 2 Then
groupsp = Cells(q, 3) - Cells(q - 1, 3)
[b8] = groupsp
Else
groupsp = [b8].Value
End If
'Range("c3:C" & q).Clear
If q <= 1 And [b8].Value = "" Then Exit Sub
If [c1].Value = "" And [b8].Value <> "" Then Exit Sub
For drow = q + 1 To ActiveSheet.Cells.Rows.Count
Cells(drow, 3) = Cells(drow - 1, 3) + groupsp
If Cells(drow, 3) = vMax Then Exit For
If Cells(drow, 3) > vMax Then Exit For
Next drow

'MsgBox groupsp
[b10] = ActiveSheet.Cells(p, 3).End(xlUp).Row - 1
End Sub

Your code is very concise and clear. You set the group distance to 3, and the data start value is automatically generated according to the calculation. I want to be able to manually input the two values of the data start value and the data group distance, which can be entered in a dialog box. Thank you!

Manually input the two values of the data start value and the data group distance, you can set a dialog box to input. This is because these two values can be entered according to the actual situation, which has greater flexibility. The function of the code is to quickly generate a series of data and charts in time after changing these two values.

If the pivot table can automatically change into a new chart with the generated data, it is also possible to use the pivot table to generate the chart.