The unreliable airspeed checklist is great for when people are disorientated or unable to control their aircraft. However if you are in level flight at cruise and familiar with the pitch and attitude requirements of your aircraft and are aware that you have unreliable airspeed it is actually safer to leave the autopilot engaged and flying the aircraft level than to disengage it and raise the nose to a pitch attitude and power setting that will initially give you a climb followed by a descent. That is of course provided the aircraft is doing a satisfactory job. We are not familiar with hand flying at altitude and even flying the pitch and power settings as per the checklist will lead to a can of worms while one person hand flies it and the other goes through the checklist. I can understand that some modern pilots with no understanding of the basics need to stick slavishly to the checklist especially when things go awry but to deliberately take an aircraft away from a straight and level situation that is under control is not desirable.
Checklists cannot always be appropriate for every situation. For instance the ground proximity checklist dictates that the wings must be level for the manoeuvre however if I am heading for the highest point of a mountain I will bank left or right if necessary to avoid it rather than fly into it. It is best if some areas are left gray so pilots can follow checklists if appropriate or ignore it if slavish adherence to them can lead to jeopardising safety.