Dangers of allowing students to resubmit assignments There are two closely related questions here:


If a student submits their assignment and is unhappy with their mark, are there any dangers (which I might not be seeing) in allowing the students to do so? If I would offer for one, I would offer for all, but should I be offering it in the first place?
If resubmits are unavailable, some students ask me to 'pre-read' or 'pre-mark' their assignment. The end result is that when they submit officially, that may actually be the second submission. Clearly doing any 'pre-marking' or the like takes time and energy and, so far, very few students have taken advantage of this until right before the submission deadline (at which point I stop because I don't have THAT much time to offer them). Are there dangers in 'pre-marking' assignments?


Note: These assignments constitute either 50% or 100% of their total mark.

One of my concerns is that the student would have lower motivation to maximize the quality of their original work and just correct what was marked as a problem area - like a production worker depending on a Quality Control Inspector and not paying as much attention to the quality of their work the first time around. Are there other issues as well? 

EDIT: I should add that these are business management subjects so student answers are not easily right or wrong but more about how they justify their analysis. Therefore, there is not an issue of "giving the right answer."
Should I be offering it in the first place?


Dangers:


You spend even more time on assignments, limiting your time for other endeavors.
Students might get into a "grade grubbing" mode where they simply re-submit marginally better answers in order to improve their grade.
Students do a poor job initially because they know they will have a chance to re-submit, and they might as well take their chances that you'll give them decent marks for inferior work.


Benefits:


Overall, students spend more time on the assignments, leading to better knowledge and ability to do the work.
You can provide helpful information to guide them to better answers (because you're seeing first-attempts). This level of grading also takes more time.
Students are happier because the stress of a hard deadline isn't so bad.


I think the benefits outweigh the dangers if you're willing to put in the extra time to re-grade. As I've said in other threads, I've used auto-grading homework for a some classes (probably not relevant in your case), but I've used the strategy that I'd have deadlines for all the assignments but that the week before the final I'd re-open all the assignments and tell the students they can re-do any questions they missed. I don't tell them I'm going to do this until I do it, in order to keep students from simply waiting until the end to do all the assignments.


  Are there dangers in 'pre-marking' assignments


I think it's great that you're being creative with the assignments (e.g., pre-marking, resubmittals, etc.). Again, it comes down to your time -- if you have motivated students who want pre-marking and you have the time, I can't see a problem with it. It wouldn't surprise me if the best students are the ones who want pre-marked work, but then again I've had some less-capable students jump at chances like that to do better.