Why must every PDF page use the same size and orientation?

PrintSimple prices and prepares each online print job from one reliable finished size and orientation. Mixed page sizes, mixed orientations, or inconsistent page boxes can require manual rotation, scaling, cropping, or imposition decisions that the online builder deliberately does not make. Export a new PDF with one consistent page setup throughout. PDF/X-4 is a useful print-exchange option when your design software supports it, but PrintSimple does not require PDF/X or claim full production preflight during this browser check.