There is no way to determine if fit all option is on or off, if a display is edited, fit all is reset and most times the display is saved again without fit all. (and you cant just select fit all and resave)

Move the fit all option to the display format screen as a checkbox and add a fit width check box option also.

(I hope you will reconsider this idea, since it has been rejected before, it would save my users lots of time and confusion)