I mainly cook meals for two or 4 which reheat well...
e.g. I'll put together a pasta sauce that does 2 days but then I'll just cook one day's pasta so that part isn't reheated.
Or if I'm doing lasagne I'll make 3-4 in those takeaway foil containers (obviously they're an eco crime but they're all handy) and then freeze 2, one into the fridge (both before baking) and then one directly into the oven.
Other things that don't reheat well, I prep in advance but leave raw and cook on the day. Things like pizza I make enough dough for two, eat one that day and put the rest of the dough in a plastic bag in the fridge where it will keep okay for 24-48 hours.
I also rotate round easy meals for one like spaghetti carbonara, salmon wrapped and baked with white wine which I think flake into tagliatelle mixed with boursin and the salmon cooking juices, sometimes a blue cheese sauce with leftover chicken.
I regularly roast a whole chicken one day and have that as an actual roast then plan various dishes where the cooking of the chicken would have otherwise made them a weekend rather than weekday meal.
And then do some random bits like a batch of Welsh rarebit which keeps beautifully in the fridge or other easy teas like eggy bread etc