typically, path balance should be between -5dB and +5/+8dB
but when the PB is outside these values, sometimes you won’t see a problem. KPI remain fine because the neighbours will handle areas where the loss of coverage happens.
Typically, in urban areas, the overlap with the neighbours is good enough -> a site with bad PB will still have good KPI.
But you will notice that the neighbours are handling traffic which is outside their “comfort” zone, and that they are having some KPI issues (sometimes).