My rule (and the code review policy I impose) emphasizes complexity instead - a 50 line shell script is great if it doesn't use if or case. (It's not so much of a strict rule as "once you're nesting conditionals, or using any shell construct that really needs a comment to explain the shell and not your code, you should probably already have switched to python." This is in parallel with "error handling in this case is critical, do you really think your bash is accurate enough?")

I wasn't the strictest reviewer (most feared, sure, but not strictest) at least partly because my personal line for "oh that bit of shell is obvious" is way too high.

This rule of thumb is clearly too simplified, even as far as the definition goes.

Sometimes you just want to execute 50 lines with little logic.

Sometimes you just have some simple logic that needs to be repeated.

Sometimes that logic is complicated, sometimes it is not.

Very true, but also student hubris is legendary. Which is perfectly fine, as we all know successful students.

But let's not blind ourselves with the survivor bias. Not everything new and very bright will succeed the test of time.

So let's take evrything with a grain of salt, and wait until the time has choosen its champions. Which might not be the best technology as we learned