I have worked alongside many Instructional Designers over the years. Some good and some not so good. I personally believe that getting something done right is far more important than getting it done on time. Ideally you want to do both, however if one has to be sacrificed, I don't want it to be accuracy. I would much prefer to be a little late but accurate, instead of on time and wrong.
I also prefer to be the library book on the shelf, rather than yesterday's newspaper. In other words, I don't want to design work that needs to be taken down or recalled tomorrow. In my line of work I want something I create to be well enough designed to have value for years to come. This not only shows that the value of my work is high, but it also gets rid of the need for re-work that often comes from not thinking ahead.