Checking bias monthly is OK, but knob dicking the adjustment pots will shorten their life. Tweaking for the last fractional mA is pointless. Great amps were biased with moving coil voltmeters for decades before digimania took over.
The bias is going to shift slightly with line voltage, time on and ambient temperature variations. Home users would do better to check bias at the end of the listening session with the amp and components are fully warmed.