SplitInto15CellsPerColumn

Sub SplitInto15CellsPerColumn()
  Dim X As Long, LastRow As Long, vArrIn As Variant, vArrOut As Variant
  LastRow = Cells(Rows.Count, "A").End(xlUp).Row
  vArrIn = Range("A1:A" & LastRow)
  ReDim vArrOut(1 To 25000, 1 To Int(LastRow / 25000) + 1)
  For X = 0 To LastRow - 1
    vArrOut(1 + (X Mod 25000), 1 + Int(X / 25000)) = vArrIn(X + 1, 1)
  Next
  Range("B1").Resize(25000, UBound(vArrOut, 2)) = vArrOut
End Sub