Average interval between dates with random blanks
One thing that stands right out is formatting cells in each iteration of a loop. Less to do within each iteration should speed things up just a bit so why not just format the entire column after the loop has done all the calculations?

I am not sure sure if you are working with more than one workbook or if that's part of an automated process but 

Set CurrentSheet = ActiveWorkbook.ActiveSheet
LastRow = CurrentSheet.Range("A" &amp; Rows.Count).End(xlUp).Row - 1
LastCol = CurrentSheet.Cells(4, Columns.Count).End(xlToLeft).Column


seems like a bit of an overkill. You are not using the CurrentSheet (pascal case vs camel case you know) anywhere in the code but you don't quality the Cells. Why not just:

lastRow = Range("A" &amp; Rows.Count).End(xlUp).Row - 1
lastCol = Cells(4, Columns.Count).End(xlToLeft).Column


Have you heard of offsets? Experience taught me that it's easier to maintain offsets rather than +1s +2s etc.

Cells(CurrentRow, LastCol + 1).Value = DateTtl / DateCount


= 

Cells(currentRow, lastCol).Offset(0,1) = DateTtl / DateCount