Are you talking about adding borders?
If so, let me clarify what you're "supposed" to do, then explain why.
If you measure your quilt at 50 inches in one spot, and 54 in another, it's best if you average the measurements, which in this case would be 52". (I personally would go back and figure out why there's a 4" difference, because that is a huge discrepancy and would be very difficult to manage without some sort of remedy, such as ripping and fixing blocks before adding borders.) You would then cut your border at 52".
The reason you don't just cut it at 54 is because you will end up with excess fabric and wavy borders, and when you go to quilt it you will have puckers and gathers in the border.
Hope this helps. If I have misunderstood your question, please clarify.
Last edited by Peckish; 08-08-2019 at 11:17 AM.