Shipping managers everywhere will tell you that in recent years, LTL carriers have become mroe aggressive with regard to weighing and correcting the freight class of shipments in transit.
Many major LTL carriers have gotten rid of the old floor scales and are now using using forklift scales. This is a large investmetn for a carrier with many terminals, but there can be only one reason that this would makke economic sense. As you might have guessed, the reson is that it's much faster and easier to weigh a pallet right on the fork lift than to spend time moving it to, and positioning it on, a floor scale. This can mean that every LTL shipment is actually weighed by the carrier, compared to only a small percentage 5 or 10 years ago.
For shippers, this means that it's more important than ever to accurately know the weight of the product that's being shipped, in addition to any packaing material or pallets. Generally, reweigh charges are not subject to discounted rates that your company or 3PL may have gotten, so even a small reweigh can mean big dollars.