25 years in business (one-man shop) and I've never had a service call on any of the four HP printers I've owned. (Designjet 2500, Designjet 3500, Designjet Z6100, Latex 365.) Mainly, I'm cheap. But also the machines have been workhorses, and easy to work on when they need service, especially when you have the service manuals.
In 2011 I had to tear down the Z6100 to replace the entire trailing cable assembly. Several years later, when replacing the carriage belt, I was very pleased to discover the helpful notes I had left myself in the service manual when doing the previous maintenance!