When I first started writing, reaching the point where I typed "The End" to mark the completion of a manuscript seemed impossibly far - a little like life itself. I'm much older now, with a growing body of published work, and my definition of "The End" has changed to the point where I never use it anymore.
There are two reason for this, one practical and the other artistic.
The practical one is the difficulty in determining when a manuscript has reached the stage where it is ready for submission. Completing the first draft creates a physical reality for the initial idea, revealing its strengths and it flaws. It also creates a sense of inevitability, making it difficult to see other ways of telling the story and I need to step away for a while to refresh my critical sense (usually by starting another story). There seems no end to the benefits of the review process. Submission and acceptance lead to further review stages, with the introduction of other minds, and the process continues until the final proof-read is complete and control is relinquished, allowing any remaining faults to pass into the public domain to haunt you each time you see the book.
The artistic reason for not using "The End" is simpler. If the reader is not aware they have reached the end of the story, then I have failed to tell it effectively and it isn't finished.