Actually I always found the spoon theory very useful & feel it describes my symptoms very well. And I do have energy limiting illnesses…
Spoon theory doesn’t assume that energy always diminishes in line with the activity, in fact (for example) in the blog that is linked above, it mentions that you can lose spoons along the way. And how infections, colds, emotion, etc can cause you to lose spoons.
I live my life pretty much along the lines of spoon theory, often without even thinking about it. eg I know a bath will take way more energy than an audiobook, so if I have 10 spoons a day, and a bath takes about 6 spoons, then I know I can only do other light tasks before / after, such as an audiobook (maybe half a spoon). Or going for an appointment would be 10 spoons or more, for example, (including getting dressed and ready (about 3-4 spoons in itself), travelling, the actual appt, procedure causing pain etc) meaning that I wouldn’t (or shouldn’t) do anything else that day.
I subconsciously operate this system in my head & find it helpful. It helps me understand why I run out of energy so quickly too: if I have 10 to start off with, but usual daily tasks take a lot of spoons, then of course I run out quickly. And it helps explain PEM for me too: let’s say I did something yesterday and used up 15, so I am carrying over a deficit of 5. so today I start with only 5 spoons instead of 10, and so I run out of energy even more quickly & just an hour or two into the day, I’m completely flattened.
the spoon theory makes a lot of sense to me. I have always thought it explains energy limiting conditions well, I haven’t found any other easy-to-understand explanation that explains it as well for me.