For safety I would not alter anything from food cooked using conventional methods and stored in plastic bags or containers.
For the different types of food the same recommendation.
This is not based on any study I have seen but rather on what I do. Thinking about the meals I make I rarely have leftovers unless I am making a roast. Everything else is cooked using portion sizes for two plates worth.
I have not found a need to rest anything. Resting is important when you cook a protein at a high temperature. The juices are driven towards the center while cooking and resting gives them a chance to redistribute. When cooking at low temperatures the difference between the center and the outside is so small juices remain well distributed.