From an interview with Marv Wolfman in Comics Feature #28 (1983):
"The Marvel problem was deadlines. I had to write the entire adaptation of Star Trek: The Motion Picture, which was 64 pages, in less than a month. And that was without knowing a lot of what was going on inside it because the first movie was so late in the working that we flew out to Doug Trumbull's and John Dykstar's studies in August and they had yet to design half the major things which would be in the movie which was being released in December. Also Marvel's deadlines were ridiculously tight because of the release dates. Dave Cockrum had to draw faster than I think he's ever had to draw in his life, and I had to write it faster."