Doing them all at once is the way to go ..... like applying one border!
Plus it lets you have one straight (well, that would be a 45° angle) seam,
and get all the joins to line up in one sewing.
You do not need to use any more fabric than doing them individually.
Just stagger add-ons enough to allow for the 45° seam.
Look forward to seeing what you are making!