I've heard it described that the sweep of a gauge can help indicate its accuracy. Something about a 0-5,000 psi gauge will give different readings than a 0-2,500 psi gauge when reading the same actual pressure. What I read was that the accuracy of the gauges has a sweet spot of sorts that it's calibrated to where at a particular pressure it's dead on. Other places along its sweep of pressures will be less perfectly accurate and this varies per gauge and per their maximum pressure variation. The widest sweep or range of gauge will give the least accurate pressures, at least in the inexpensive gauges. A narrower range of pressures may be more accurate, depending on quality. So quality, how they're calibrated and maximum pressure reading sweep play a part.