Individual pitch accuracy is important, but a continuous press chain also needs controlled accumulated length over a long measurement span. This is especially important when two chains must travel together.
Manufacturing contributors
Plate-hole position, pin and bushing geometry, assembly fit and measurement method can all influence accumulated chain length. Wear during service adds another source of elongation.
Installation contributors
Worn sprockets, uneven tension, poor alignment, contaminated lubrication and different wear histories between left and right chains can create tracking problems even if a new replacement chain is dimensionally correct.
How to specify the requirement
Define the measurement span, preload or measuring condition, allowable accumulated deviation and whether paired chains must be matched. If an OEM drawing provides a method, use that method rather than a generic roller-chain inspection rule.