Some of these items look to have been replaced over the years and some I am not so sure about.  For example, I recently replaced the H2O heater and noticed one of the heat exchanger hoses was new the other was not.  For hose clamps, everything I touch now sees a new Scandvik ABA 316 hose clamp, including at the thru hull valves (where many had one even though the length of the barb could support a pair and at the glass shaft log and packing gland.
I would like to focus on replacing the hoses that appear dated or show signs of abrasion that could leave me stranded.  The cooling and fuel hoses some to mind.  Does anyone have an inventory of the size and length of the primary fuel supply and return runs and coolant runs to the hot water heater (these look to be 5/8")?  I already have the information for the hoses that start and terminate on the diesel itself.
As for the various in-line vents and check valves, do folks proactively replace these as well?  Which ones could leave you stranded should it fail?