In Mx CBs are not pulled out unless a specific AMM task requires that action.
All Mx personnell are aware of this aspect.If they were not then they dont belong in Mx.
Of course we are all aware of this but with time pressures and people prepared to use "experience/professional judgement" deviations from the manual do occur and can have terrible consequences.
Example: the Helios flight where an O2 select switch had been left in mx mode instead of flight auto.
Example: SA carrier where CBs were pulled different to manual recommendations, then left pulled, resulting in 4 engine flame out (fortunately on ground).
It's ironic that in a job that really does require experience and professional judgement, using it can be fraught with dangers.