This is all fine and good. Short term contracts should yield best value overall, if only to reward more frequent players.
I used to have several Idea Factories out in earlier levels, but stored them all because the goods often spoiled. I liked the Idea Factory because it's the only industry in which a 1-hour contract is available. No matter how busy I am, I rarely go more than 2 hours without checking my phone during work hours, so the 1-hour contract was the most convenient for me throughout the day. However, I found that the spoil time was not consistent with Idea Factories - sometimes goods would spoil a few minutes after the 1-hour mark, other times they would last for 2 hours (and not a minute more). This, of course, might be just my imagination, but when I had nothing but Idea Factories out it always seemed to me that I returned to spoiled goods no matter what I did. I also noticed that the game did not alert me when the Idea Factory contracts finished.
Greenhouse goods, on the other hand, take much longer to spoil and are much less expensive. I prefer Greenhouses now. The longer spoil time is especially convenient while I'm sleeping for longer than normal, i.e. on weekends.
Even though I no longer use Idea Factories exclusively, I still run the 1-hour contract whenever I know I will be looking at the phone every hour. That's really the most convenient contract there is in terms of time/goods received, despite its outrageous price ($215 for 100 goods). Whatever you do with the in-game math, please do not eliminate the 1-hour contract (though I wouldn't mind if you made it cheaper!
).
-lp