AC refrigerant filling using sightglass bubbles

How many times have you heard someone say top off the refrigerant or fill it until the site glass has no bubbles that means you’re good. ???

this series of videos runs through this 2007 Prius that has a beautifully clear sight glass but only 148 g of refrigerant in the system.
Plenty of condensation of water dripping out from the evaporator to the ground like a normal good operating air conditioning system
Customers only complain when it’s hot it doesn’t cool well and the customer is a technician at the shop that I service and I just serviced this vehicle one year ago so I know exactly how much refrigerant was put into the vehicle