unequal distribution of breather means unequal distribution of clamping force. vacuum cant be fully realized where the bag can pinch off on a part or itself. from my perspective the entire laminate being cured should be covered in breather and should have a clear path of breather to both vacuum source as well as vacuum gauge(which is preferably opposite to the part of the source)

test it. make a bag and put 3 ports in. one for source and 2 for gauges. spread them out about 2'. route breather from the source to one gauge. see what you get. on a good day it might be close to equal but it is not repeatable.