What did you use in the Navy?
"Butt splices are a guaranteed point of failure and source of endless headache."
Only if they were made by someone who didn't know how to make them properly. If you use a good tool, good quality butts, and use them properly? They are 100% reliable and that's pretty much "forever". Use the "500 for $5!" set from the auto chains and use them sloppily, and they're land mines.
Butt splices are verboten in the Navy. I'm not saying you won't ever find one because yard dogs will sometimes take a shortcut, but they are replaced the moment they are discovered. If somebody signed off on work where a buttsplice is found they could be fired. A butt splice on a naval vessel is enough to get your ass in deep dookie. Ditto wire nuts. No ifs, ands or butts. Yeah, you see what I did there...
Butt splices of any kind, regardless of manufacture or perceived quality, are not acceptable to any electrician anywhere. If one of my electricians or technicians ever used a butt splice in any vessel or any factory- they would be shown the door on the spot. Gross incompetence. It's the equivalent of a mechanic using pliars to tighten a bolt, or a carpenter beating in nails with a crescent wrench. That person is simply not qualified to work here, wherever "here" may be.
The proper way to splice a wire (not in a cabinet), in the rare event you must, is to use two ring terminals with a bolt as I described. That is the same way motors are connected inside the peckerhead. If you're talking 18ga or smaller, then the wire is paired side by side, solder joined, and then crimped and sealed. On land, you will often find wire nuts. Depending on code, that is sometimes acceptable providing they are taped properly.
What I see on small boats in marinas is about on par with what I'd expect from shadetree mechanics and DIYers. If you want to use butt splices, this is America and you can do whatever you like on your own boat. But there is a right way and wrong way. The right way is right for a reason. People who do these things for a living have to face the consequences of the wrong way.
In a simpler answer: You pay for repair work by the hour. If a system takes twice as long to troubleshoot, or you keep paying to replace parts until the actual problem is found, then that $5 butt splice wasn't a great deal after all.