My biggest fear is that the Jell-O wont firm up in 3 or 4 hours. There have been times when it hasn't. Notably this past Thanksgiving. There is some guess work in the amount of liquids being used, from the Cranberry juice from cooking and the crushed canned Pineapple. To save and resurrect what might be a failure, I add the contents of another package of Jell-O to one cup boiling water and dissolve well. Then mix and thoroughly combine this with the failed to set Jell-O. This has worked on every attempt, the Jell-O has firmed up and has saved the day.