Simple, adaptable, and concise.

It makes a copy of "key". It's the same as key[::]; when dealing with lists (or other mutable types) it prevents alterations affectiong the original list, as far as I know this isn't a problem with the immutable strings in python so it's probably just habit.

if there's one thing you could change from this approach it'd be using * instead of / just for that imperceptible performance gain from avoiding binary division

But aren't we essentially looking for the time in 10ths of a second that is closest to the apex of the curve of height against time. Since the curve is parabolic if we take the time to reach the highest point when v has deaccelerated to 0 then the nearest 10th of a second either side of it is our recorded answer?
I've not touched calculus in years so my reasoning could be a little off.

Isn't that the fault of the kata creator setting bad initial variable names?

It's a nice solution, I wasn't aware it could take a default, I took a while to figure out at which point I realised I had misread the kata description and there was only one single error that you needed to find...

Why on earth did you use lower case L as a variable name?

I published it initially to see how this whole beta process worked as I didn't really get the whole structure of tests.
there's something else I wanted to add to the test which is a little more challenging but i wanted to try the simpler version first and get basic feedback.
Honestly I've never cared much about points.

OK, that should do it now, hopefully.

I couldn't think of a way to randomly insert gaps.