When people talked about crank length, I found it silly to think that people can feel the difference in 5mm. Then I was riding a new-to-me bike, and I couldn't get the seat height right. I kept raising it and lowering it. Then I realized the cranks were 175. What a difference. And the difference is really double, because a 5mm difference in radius is a 10mm difference in diameter. And then there is all the trigonometry of our knee angles etc, so it really does make a difference. I've tried shorter cranks, and they feel a little funny but not uncomfortable. Once, a friend loaned me his bike for a day ride we took together. It felt a little off, so I checked, and yup, 172.5 cranks. They weren't so long as to annoy, but I do not like 175.
[MENTION=73614]rhm[/MENTION] once saw a "junior" crankset on ebay in France, and he suggested I buy it. It had 155 cranks. Later, he confessed he was hoping I would dislike it so I could pass them to him. Well, I like them. I have them on my street fixie. It's geared low, so being able to spin fast helps. I had to raise the saddle, of course, but that's OK. I loaned that bike to a nurse visiting NYC for the pandemic. The nurse said they'll return it, but I know I might never see it again. We will see.