In our shop they visit on a yearly basis and check to ensure we are using the correct PSI when apply sheeting and graphics....compression rollers are in good shape...prepping the substrates correctly, storing the vinyl properly...using the right inks with the proper substrates/sheeting, have all our signs stored and labeled. Printers and laminating and curing time process acceptable. They will also have you show them each step i.e. pull a print when screening, prep the substrate...apply the sheeting etc.