My goal is to calculate a sum from the same column on ALL worksheets. I
already know I can select multi sheets in an existing formula:

=Average(start:end!AA32)

I am always adding worksheets to specific books and I would like to not have
to update the formulas. I want a wildcard or 'select all' in the formula.

I know I could insert the new worksheet between the existing start and end
sheets, but the new sheet would always need to be at the end.

Thank you.