Connets, this should be good. Refresh my glass memsahib & some crispies to accompany would delight. Damn, I told myself not to start like this. Look, I love the legal take but it really starts to complicate in the search for clarity. You throw in the words routine and routinely. Boy, open the flood-gates for discussion. We have, in professional Air Transport Aviation a set of guidelines in our Operations Manual. Normal, Supplementary Normal, Non-Normal and Emergency. Since we study, get regularly checked, have the opportunity to regularly practice most considered events, one might venture to question what is considered to be routine.
For example, a critical failure is the loss of a powerplant at Decision speed on a limiting runway. I was thrown this failure routinely on every check I ever had to perform. It was a failure that would be routinely briefed for & even rehearsed in the form of briefing & touch drills to the point that it was almost expected on take-off & should not cause surprise.
As others have expressed, it is our responsibility to check that the aircraft is correctly configured & switches are in the normal position as a matter of routine. If we are presented with an aircraft that is being dispatched by Engineers in accordance with the Minimum Equipment List for any number of reasons, we are, again, responsible for total understanding & accepting the aircraft with a full brief as to what is expected of us. see what I mean Connets ? It might be routine to accept a supplimentary non-normal or even non-normal configuration of switches.
Most pilots would not expect to see the Px control in Manual during pre-take off checks. If it was, we would ask Engineers to explain. Manual would require manual control of the outflowvalve through the Clb/Dec switch & requires practiced and even artful technique. I would not consider this to be a routine practice.
Loss of PX at any stage requires the operating crew to don Oxy masks & regulators & establish communications (with each other) . That part is a memory drill. We would then try to establish the cause & take manual control of the outflow valve, if that was the problem, by first, placing the PX Control switch to MANUAL.
BOAC, all bleeds off wouldn't half be felt in most ears. Engine bleeds off might be used in the supplementary normal case where max thrust from the engines is required. Remember the old Boeing procedures of configuring the system in the form of a letter "C" & then re-configuring, after take-off in the "reverse C" ? Switches, definitely in a non -normal position but, from Connet's point of view (legal-eagle), possibly a routine event outa some airfileds ?
Trust that might help clarify your question Connets.