At low values the output is recognisably the input with the surface reworked. At high values the input is a suggestion the model was shown before it made something else. Everything interesting happens in a fairly narrow band in between.
This is the single most useful dial in plate-locked work, because it is the direct trade between fidelity to the lock and freedom in the frame. Too low and every variant looks like the plate; too high and the product stops being the product.
Find the value that holds your silhouette on the hardest shot, write it in the set specification, and stop adjusting it per frame. Per-frame tuning is a drift source dressed as craft.
What denoising strength should I use for product work?
Low enough that the silhouette survives the overlay test on your hardest shot. Find it once, write it down, and hold it across the set rather than tuning per frame.
Why not tune it per frame?
Because a different value produces a subtly different relationship to the plate, and forty frames at forty settings is a set that drifts for reasons nobody can reconstruct.