If you want to be effective, it's important to produce at a high rate. It's almost impossible to produce at a high rate, if you are also trying to produce at a high standard. So lower your standards and things become easier.
As with many things there is a balance. If you lower it too far, work becomes sloppy. If something is very critical, it may be okay to spend more time on it. But most people would be more effective if they lowered the expectations they have for themselves.
Writing is a great example. I'm not a great writer, primarily because I don't practice writing enough. I don't practice writing, because I have the idea that it must be very good and thus require a lot of effort.
When writing emails, I have found a good question to ask is: "Does it get the main point across?" It may not be a well written. It may not be persuasive. But if it gets the main point across, it should be reasonably effective. And if that's the case, it's best to send it and move on.
Practice lowering your standards. And create more with ease.