Having actually sailed, I can attest to a couple of things: Commercial-grade sailboats are filled with gremlins, and the ocean is enormous.

I can count on zero hands the number of times I've been on a sailboat where everything worked perfectly. This is a function of cost moreso than criticality, but the amount of time and energy required to upkeep a sailing appliance that consistently endures some of the worst things nature can throw at it would practically require replacing every part with every sail.

Sailboats shake, vibrate, and shudder as they are subjected to wind and waves. Topside parts enjoy the added joy of being continuously subjected to sun, salt, and wind.

In short, things break. Slightly longer, it is fair to expect that on any given day, something will be broken. Whether a car that holds a mainsail to its mast, or a fuse that powers your navigation equipment, or what have you, those systems are great and wonderful so long as they are operational, but if you are halfway across the Atlantic ocean, hundreds of miles away from the nearest land mass in the dark, there is no Radio Shack to visit, and no way to find it without having to fall back to a compass and some celestial orientation.

No matter how good they are advertised as being, absolutely zero systems should be considered trustworthy in a big sea.

I was right there with you until you mentioned Radio Shack. I had to look at the date to see if I woke up in the 1980s, as that's really the last time Radio Shack would have been useful (unless you want to buy a shitty mobile phone). Since you used proper name upper casing, that's what I assumed. Especially since you're talking consumer sailing boat where the actual radio shack of a boat is less a shack and usually just a radio unit bolted into some dead space so it won't take up usable space from something else.

Radio Shack was a placeholder for the more complicated and technical explanation. In reality, replacing boat parts is done by manufacturers and marine shops that are usually located in or near marinas, much of the time requiring someone to order the parts special except for popular makers of products.

There is no Radio Shack for marine electronics, but it'd be great if there were.

There is no Radio Shack for anything useful is the gist I was going with. An old fart recognizing another old fart. It's kind of a shibboleth at this point.

If you are doing celestial navigation and need second-level accuracy you can correct for it by adding the extra seconds.

And my understanding is that if celestial navigation isn't good enough you are probably close enough to land to just navigate based on sight and map.