Re: " There was an old joke that any component on a cart"
"It's actually called the "One horse Shay" design, after a short poem about such a cart."
It's a poem by Oliver Wendell Holmes and it tells a completely different story. It begins "Have you heard of the wonderful one-hoss shay, that was built in such a logical way it ran a hundred years to a day?"
It's the exact opposite. The wonderful one-hoss shay is made from the perfect materials for every single part. As a result it lasts for an entire century and then every single part wears out at the same time.
It's worth reading, especially if you like working in wood.
Now in building of chaises, I tell you what,
There is always somewhere a weakest spot, —
In hub, tire, felloe, in spring or thill,
In panel, or crossbar, or floor, or sill,
In screw, bolt, thoroughbrace, — lurking still,
Find it somewhere you must and will, —
Above or below, or within or without, —
And that’s the reason, beyond a doubt,
A chaise breaks down, but doesn’t wear out.
(It doesn't mention iPhone batteries.)