My editor at Del Rey is a very lovely person. (Actually I haven't met her in person yet...hopefully at AX)
She always thanks me for "doing a quick job" or "replying so fast with the additional translation notes."
Yes, I usually turn in things before the deadline. (Well, now I do. I didn't turn in essays before the deadline in college)
This is for many reasons.
1) I like to get on things when they come to me. So when she sends me a question with a simple answer, I usually answer as soon as the email comes. I also don't want to sit on it and forget about it.
2) I have dreams about the work that's sitting on my desk. Not dreams, they are nightmares. "Ugh, I still have 3 translation jobs to do..." "The novel text is chasing me..." Stuff like this.
3) This week I have another reason. I didn't want any deadlines on my birthday. It's already bad enough that I'm working at the restaurant on my birthday. So I recently turned in something for Broccoli. My editor made it due on my birthday! And I think he knows it's my birthday too... I wonder if that was my present. "Here you go, the deadline for this manga. Happy Birthday."