Yeah, right, of course it is.
The first time you do something, no matter what it is, will end up being perfect, right? As anybody with any life experience will tell you (in a polite way), is no. This is the basis for editing.
When you have created your masterpiece, you might want to go back and take another look. Don’t do it straight away though. Give yourself some time away from it, so you can see it with fresh eyes. Then you can spot the mistakes you’ve made; words missed, poor punctuation, grammatical errors and other such mistakes.
Next, and this is where you go into more depth, look at the language you used. Is this what you wanted your characters to sound like? Are the sentences too long? Tip; try reading dialogue out loud. If you’ve run out of breath or get stuck on a section, it’s probably too long.
The next issue is a little more subtle; does the balance feel right between descriptive language and dialogue? This is tricky as it depends on the individual writer. We all have our own writing styles. Some are descriptive heavy, like Tolkien for example. Others prefer to paint a basic picture of the world at that point in the plot and are happy to leave it at that.
Finally, look at what you have written and ask yourself; is this the best I can do? In the heat of the moment, we need to get the writing down on the page. Yet when we look back, it seems to be lacking in sophistication.
Editing is like digging a mineral from the earth, washing it and then cutting it to make it into a jewel. The raw beauty looks great, but there is nothing so inherently beautiful as a cut diamond.