We have long had the convention of beginning our layout names with the number of the sheet, e.g., A1-1 1st Floor Plan.
This is no longer needed.
PM has a feature to "Show Names & Numbers" in the Navigator. It's had this throughout the life of PM3/PM9, but in the beginning, plot file names would not include the number even if it was displayed, so we had to put the numbers in the names to get the plot files named correctly.
Two things have changed. First, if you plot a layout with the number showing, the filename will have the number. (I don't know when they fixed it.) The same goes for DWGs. Second, we don't plot anymore; our archive files are multipage PDFs where the individual layout names are not seen.
So: Switch your Navigator tree views to "Show Names & Numbers" using the flyout at the bottom of the tree; and stop putting the numbers in the names. I recommend fixing the names of layouts in running projects; it doesn't take that long.
I have updated the templates with this change.