Cambelts? Don't start me. I was designing auxiliary gear drives on diesel engines during the period when cam belts were becoming increasingly popular.
They were a shoulder-sloping cost reduction for makers of smaller engines. Cheap easy initial build and after that the consumer, most often a secondhand buyer, bears the cost of maintenance and the trade gained a nice little earner.
People were popping into the office trying to sell us chains or belts. The belts were being sold as quieter even though we could already buy chains that were quieter than belts and lasted the life of the engine.
Things are not always what they seem.