Craftsmen care about the little details. It should be the opposite of doing things with speed. But, somehow caring about small details makes you move faster.
Depth increases your bandwidth. Attention to little details will make you obsessed. Your task will take up more space in your mind. There are scaling advantages to obsession. The popular belief is that it's better to take breaks every hour or so. I disagree. If you work for 5 hours straight, you will get 8 hours worth of work done. You download the context and open up a new dimension.
There is a hidden depth in quality. Polished details make a product feel very different. It's unquantifiable, so we tend to dismiss it. But this is how the best products (Tesla, Apple) or the best programming languages (Lisps, Rust, Go) give such a feeling of awesomeness. Eventually, your goal is to do great work. Caring about the small details will get you there faster.
Polishing frees up your brain. Every new item on your stack becomes an open thread that won't close. Details are how you close that thread. If you think your work is perfectly done, you will sleep at night. Otherwise, it will always be there, nagging you in a subconscious part of your brain. Maintenance also becomes much easier. The code is tested, readable, modular and errors are handled.
Obsessing about the trivial will raise your standards. The habit of getting the small things right will make quality automatically improve. What previously required a lot of conscious effort becomes second nature. As with most skills, it will compound, and a thousand small improvements will have a tremendous effect on the quality of your work.
It's obvious, but going the extra mile is often most of the fun. What's less obvious is that this feeling of satisfaction will feed into the other components of craftsmanship. Self-reinforcing the depth, polish and finality you bring to your products, reaping the benefits of excellence.