c) After Takeoff checklist.
The After Take-off checklist makes no specific mention of checking the pressurisation instruments - only to set or verify that the engine bleeds and air conditioning packs are operating.
It could be argued that is a major flaw in the Boeing published checklist since numerous observations in the simulator often reveal the crew do not specifically check the
pressurisation instruments as well as switch positions. - although the actual checklist items are self challenged and responded to by the PM. If the Helios accident crew had bothered to look at the pressurisation instruments during the initial climb after the flaps were up it is likely they would have twigged something was wrong with the pressurisation early in the peace and taken appropriate action. More often than not, simulator observations reveal the PF is too slack or busy on other things to verify that verbal checklist actions of the PM have indeed been done correctly.
Also there is often a tendency for the crew to concentrate only on what the published checklist states and not use their commonsense to keep an eye on allied items appropriate to the systems the check list is written for.
The manufacturer designs a checklist system with the understandable assumption that competent trained crews will use it. As many accidents have proved, not all crews are competent.