I agree, for many applications, it’s far easier to cut a familiar recipe in half or in quarters than it is to try to cook portions exactly divided for one or two.
That way, we wind up having, say, the same entree two nights in a week, not four.
I try to vary the vegetables I serve, and to alternate meals, so I don’t wind up having to cook but a few nights a week.
For something like pot roast, I cook a small roast with a LOT of vegetables, but tend to only add enough potatoes for a few servings. That way, when it’s time to freeze leftovers, the potatoes (which don’t freeze very well, IMO) are gone.
If you cook potatoes, cook a few extra and dice the leftovers and brown them with a bit of onion for hash browns the next day.
For me, it’s KEY to figure out what we really do enjoy eating, and stick to that. Variations are fine, but I find it best to keep experiments on the small side so, as you say, we don’t wind up eating the same not-so-yummy stuff for a week.
Meat-wise, chicken thighs are handy, because each one can be a portion, so that’s easy to determine as you divide things up for service.
I guess the main thing I do is determine how many portions I’ll wind up with, given the amount of meat in the main dish. For us, four ounces (before cooking) is plenty per serving.