What's perplexing is when companies have you do multiple timed coding exercises, remotely. (I'm looking at you, Uber.) This is grade-school-style regurgitation of algorithms, not a window into process.
I agree with you that they're great for stretching your abilities, learning new patterns, and becoming a better coder. I've gotten better from them for sure, and have a long ways to go yet. But whether they're a good assessment depends on how they're administered.
Exactly, I shy away from the "they failed the test they suck" way of thinking. I've worked with many developers who under pressure with a whiteboard can't produce squat, but sitting in front of their machine coding can work miracles. It simply isn't a great go/no go indicator for someone's true skills.
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