AllMenAreIslands But you're kind of answering a different question.
You're talking about what energy to make in the kitchen - and all your points are great.
But I'm talking about when to eat that food. The main options being either (a) eat it immediately, or (b) eat it later.
There are many people saving it for ages, which has a few valid reasons - previously mentioned by a few people, to finish an event if you're running out of time, and Chani just suggested to race through the start of a region to reach the repeatable locations, which is a neat idea.
Aside from those - if you already have enough natural energy income to do the events, then aside from Chani's suggestion to race through the start of a region, there are not many other reasons to save.
But there are reasons to use it. Because it devalues. It's like saving $1 from 1920 - back then it was probably enough to buy you a week's worth of food, but now it'll only buy you half a cup of coffee. Yes, it's still worth $1 either way, but the value of that $1 changes due to inflation.
Yes, my Berry Cake will always be worth 450. But early in the game, when it takes me an hour and a half to make that amount on my own, that's pretty valuable. When I posted previously it took me thirty minutes to make that same energy on my own, and now it takes fifteen minutes. What that means is that the value of a Berry Cake has decreased because it's not worth as much, due to the inflation caused by the improvements to your camp equipment. When you've been playing for three days, one Berry Cake is a huge amount that can clear you half a level, increase your experience and get you significantly closer to more camp equipment. When you've been playing for three years, that Berry Cake is a drop in the ocean and you'd hardly notice it. So if you use it straight away, it' valuable. If you save it for three years, it's practically worthless. Even though it is indeed always worth 450.
It's completely independent of how long it takes to make the Berry Cake in the kitchen. The comparison is how many minutes' of energy production it's worth, same as how many minutes' income that $1 is worth. Back when you earned a dollar in a day, $1 is really valuable. When you now $10 in an hour, that $1 is a lot less valuable. Pretty pointless saving on to it when you could have invested it (in camp equipment!) ;-)