What always works for me.
A proper watering session always consumes 25-30% of the pot size. So let’s say you’re using a 3 GALLON pot. A good slow soak 8-13 minute watering session, will usually cause the pot to absorb around 2-3 QUARTS with a small amount of run off at the end. (3-5oz).
My 4 gallon pots get 1 gallon each watering. 5 gallon pots get about 1.25 gallons.
The only thing that changes is the watering FREQUENCY depending on how the plant is pulling up water based on its size/growth rate.
Best watering practice is water SLOWLY and evenly, with 2-3 minutes inbetween to allow even saturation. (Think of light/medium rain in nature).
My watering session of 4 plants usually takes 19-26min.