I have a nine radiator system, with TRV's on all but the hall rad, where the wireless thermostat is located. I have never, ever balanced them, they have always everyone one, got hot enough, even before I added TRV's. Now with TRV's fitted, I think I have even less reason to bother balancing them, because even if they were balanced, the balancing would only limit the maximum flow, whilst the TRV was wide open. Once the TRV begins to be satisfied, begins to close, the balancing makes little or no difference, in my view.