Witn txv system, the reciever holds a reserve of liquid refrigerant waiting to enter the evaporator. Because the phase change (liquid to gas) at the expansion valve is what provides most of the cooling, you dont want to allow refrigerant to enter the evaporator as a gas. That's why bubbles are bad. But what you don't know is what happens when the system is stressed. The mfr has supposedly done the math and the testing to know how much is required under all conditions. So its best to go with that recommendation, even if it means there is some liquid refrigerant backed up in the condenser.