they already know where is staff shortage so they will prefer local candidates. and if local candidates of that cities are less then they will send candidates from nearest cities.

and guys city of preference doesnt play a role in selection.
academic record , test score plus interview matters.

for example if u r resident of jehlum and abl needs an employee in jehlum then they will not just appoint u. they will look for good academic record , test score plus interview whether that person is from islamabad or rawalpindi or attock.

i hope i cleared my point.