I've $11,000 invested in my 6.0 when you consider the cost of the new truck engine option and the mods needed to make it reliable and strong. I often change oil after each trip which usually equates to 3,000 to 6,000 mile intervals. This gives me a chance to poke around and make sure everything is in order. The comfort that gives me is worth more then $130 knowing that my chances of traveling trouble-free are much greater. Admittedly that is a personal preference of mine and if your methods are satisfying to you then you are also doing the right thing.
I also have other vehicles, some lawn equipment and a tractor that get regular maintenance. One of the reasons the guys at the truck inspection station know me by name is that I bring them 55 gallon drums of used oil that they use to heat their shop.