Power Query Max Date from large data set

Good Afternoon Powerbi team,

I was hoping someone could educate me on the best practice for my issue. I have a solution but I am positive it is the most memory inefficient solution.

Solution is being built in Excel 2013.

The model I am building gets data [an excel file per month] from three folders, so for a full year it is 36 files.

I need to identify the latest date/month these are for so I can apply my forecast to the following months.

For a dynamic solution I am simply referencing the dataset detailed above, remove all other non date columns and filter on the latest value and convert to a list. The problem is everytime it refreshes it checks every file and is time consuming.

Other option is of course to have a named range which the user updates, but I'd prefer a dynamic solution.

Anyone have any ideas?