It's true for most machines (as in, energy conversion). The main exception would be heating, and even then, it's usually that the optimum performance is just r

It's true for most machines (as in, energy conversion). The main exception would be heating, and even then, it's usually that the optimum performance is just really close to the top performance; e.g. imperfect combustion of more fuel being less efficient than perfect combustion of less.