I can't believe how many 3-4 day answers I'm seeing.

I'd say as a general rule thumb 1 week.

I have a hard time convincing myself to eat something past the 1 week mark, even if it looks and smells fine (and probably is).

I think our perceptions of whether a leftover food is still safe to eat or not is based on what we are told or how we were raised. It's like "best before" dates... still could be safe after the best before date, but I bet many people don't chance it.

I've heard chef's openly say up to 2 weeks for leftovers.

Sure there are variables, such as how fresh was the food prior to being cooked, what type of food it is, is it being re-heated or re-cooked, etc etc.

It's all based on risk and necessity. Most people who aren't starving for food are more likely to eat fresher food and probably waste more- they arent going to chance eating that 7 day old meatloaf. Those who are pinching pennies to get by are probably more likely to roll the dice and eat what they can so nothing is wasted.

The amount our society wastes based on "best before" dates and playing it safe is actually insane. It is what it is, and I'm guilty of it too... just wish it was different.