all alignment centres are ripoff in Islamabad / Rawalpindi except for a few who arent well known, most of the mechanics at these shops use there inherited abilities of alignment to adjust two wheels in a row rather than opting for a guage or a rod on back wheels.
Unless you have a fixed axle setup at the back, the basic of alignment says that to adjust one wheel, you need two reference points, here one reference is back wheel and other the opposite wheel.
what if the "andaaza lagane wala" has parallax in his eyes, the way an individual sees two aligned objects varies for everybody. so i recommend to use only those who use all four wheels to align a cars front or back