Frame Width % is an essential tool if you would like to change the width of a particular frame.
THINGS TO KNOW:
DESIGNER TIPS:
ONE
Frame Width in Columns
Sometimes it might seem logical to add extra Padding to Columns when designing on Desktop. However, adding extra Padding to Desktop might not consider your Mobile alignment. Since Width % is not active on Mobile it is a nice solutions to adjust Columns widths on Desktop without having to consider or test on Mobile.
TWO
Frame Width over 100%
You may wish to make a Frame smaller (less than 100%), or, you may wish to increase the frame width (over 100%) to make the Frame overflow it's normal size.