A tap for the kitchen sink that has a separate temperature control knob and a lever to control the flow of water.
The temperature knob would control the mix coming in from the hot and cold pipes. The flow lever would regulate the amount/pressure of the water coming out of the tap. This way, the temperature could be preset when washing or rinsing dishes. You wouldn’t have to worry about the lever getting pushed too far in one direction (too cold) or the other (scalding).
In the case of two knob tap, it’s a nuisance to adjust the temperature with two knobs. And once you get the temperature right, it’s a waste of water to just leave it running.