Yes, Go from the passenger rear the drivers rear, passenger front and then drivers front, take your time, i was suprised at how much air came out of a new system. when its done right the brakes feel great.

This is usually the time when the brake warning light gets tripped --when bleeding out brakes and the imbalance of hydraulic pressure on the differential spool inside the brake valve shifts (most often to the rear brake circuit becuse it's the first circuit to begin bleeding out).

This simple device can save you a lot of frustration during this process;

https://www.musclecarresearch.com/brake-valve-tool

Apparently GM cars had springs that would re-center the piston/spool.  For Fords it is not as easy as once they are tripped, they will not re-center on their own without creative bleeding.  In this link Mach428 describes a procedure I have used  http://www.network54.com/Forum/74182/thread/1301100185/porportional+valve+69+mustang 

The device Ultratang shows prevents the spool from moving and can save a lot of time and frustration.  Some here have made their own.