I have a multi-worksheet workbook and on the last sheet I want the sum of
certain cells from every worksheet. I.E. on the last sheet I may want in
cell D3 the sum of cells D3 from all the other sheets. I have been doing for
example =Worksheet1!D3+Worksheet2!D3 and so on, but that is cumbersome and if
I insert a new worksheet I have to manually add it to the formula. Is there
a quicker way?

What if the cell in the summary page does not match the cells in the other
worksheets, like I want the sum of all D3's in cell F5 of the summary?