Break a list(of T) into arbitrary fixed chunks - with or without Yield.

listChunking

'Usage example:
'Dim setsOfList = OriginalList.Chunk(3)
'For Each innerList In setsOfList
'Do stuff
'Next

<Extension()>
Public Iterator Function ChunkData(Of TSource)(source As IEnumerable(Of TSource), chunkSize As Integer) As IEnumerable(Of IEnumerable(Of TSource))
    Dim _chunkSize = IIf(source.Count < chunkSize, source.Count, chunkSize)
    Dim i = 0
           While i < source.Count()
               Yield source.Skip(i).Take(_chunkSize)
               i += _chunkSize
           End While
 End Function
 

<Extension()>
Public Function Chunk(Of T)(Source As List(Of T), chunkSize As Integer) As List(Of List(Of T))
Dim _list As New List(Of List(Of T))
If Source.Count < chunkSize Then chunkSize = Source.Count
    For i = 0 To Source.Count Step chunkSize
        Dim remainingList = Source.Skip(i + chunkSize).Count
          If remainingList >= chunkSize Then
                Dim innerlist = Source.GetRange(i, chunkSize).Take(chunkSize).ToList
                _list.Add(innerlist)
          Else
                Dim innerlist = Source.Skip(i).Take(chunkSize).ToList
                If innerlist.Count > 0 Then _list.Add(innerlist)
          End If
        Next
    Return _list
End Function

Please note the non yield version does not take advantage of call backs, it simply provides you a list of lists, each one representing a fixed number of items from successive sections of the list.