Several comments: We seem to have wandered far afield. To compare maintainability, you have to compare like to like ... aircraft that perform the same role. (not roll, btw) Comparing a Cub to a Concorde is ridiculous.
Second, we must consider the whole maintenance picture from parts supply chain to aircraft ready to go on the flight line. A single source manufacturer unable to keep up demand for unique and critical winglenuts will keep a whole wing of strategic bombers grounded in North Dakota. Also, do they need special tools or skills. The '60s A-5 Vigilante designers considered the complexity of their supersonic nuclear bomber, and designed a companion trouble shooting cart that could plug in and diagnose tricky systems ... much like the computerized auto diagnostic bench machines of the '80s, now reduced to hand helds. The only problem is the North American testing unit, the size of a tiny car, was susceptible to salt air, and crews spent more time trouble shooting the test unit than the airplane.
McDonnell designed the F-4 Phantom to be maintained aboard Navy ships with limited access to parts warehouses, so used the same fuel transfer pump in multiple locations ... needed to move JP between the many internal tanks and up to three external droppable tanks. The problem arose when the Air Force found their dozens of fighter bomber designs developed in the '50s unsuitable for wars like Viet Nam, and also ordered the Navy Phantom. Their supply philosophy had the AF order several years of pumps in advance of the need, and suddenly there were none available for the Navy as the AF had the plants locked up with production contracts. We found Navy and Marine aircraft unable to carry more than one external tank, and sometimes none ... just because they didn't have enough transfer pumps on hand.
Touching on the Spitfire vs. Hurricane issue, despite using the same Merlin, Mitchell based his machine on elegance and lightness, using stressed skin, aluminum monocoque construction, much of it with compound curves requiring special tools and skills to form ... like a thoroughbred race car. By contrast, the Hurricane used welded steel tube structure, and skins were not structural ... just tacked on with screws or Dzus fasteners, or even fabric over wood stringers. It should be obvious which would absorb more punishment, and be easier to repair ... also requiring less skills or tools.
Finally, Jeffery Quill's "Sigh for a Merlin" describes the difference between the Rolls Royce built Merlins, and those licensed to Packard and US manufacturers. The British tooling and techniques had sloppiness and variations in them, and those assembling engines were diligent craftsmen, measuring and matching things like pistons to fit bores and with equal weights. Beautiful work, but time and skill intensive. American machine tools were much more precise, and this hand fitting and matching was dispensed with.
Cheers, Bob