That depends entirely on what it is and how much other stuff we have in the fridge at the time.
Well, since I live alone I typical take it. If I leave it then it will go bad and that is just wasteful. ;)
If there are leftovers in my fridge, I will eat them because if I don't it'll just end up growing mold. My daughters put food in little containers but never look at them again. Lucky for me though, cause then I don't have to cook as often.
Have kids would leave it for them.
I take it, but then my husband and I each have our own refrigerators and my son is grown and has moved away from home.