How much wood can a woodchuck chuck if a woodchuck could chuck wood? As much wood as a woodchuck could chuck if a woodchuck could chuck wood.
You give what is needed to fully get the medium wet. A little runoff is fine in soil (don't want to leach those amended nutes you paid for). In soilless you want a minimum of 10% runoff (waste water). Dry pockets are the devil (over time a potential source of big problems).
If you water at the same loss of weight -- can also judge by dryness of top soil -- it will require the same volume of water to get the job done, so you can learn the correct volume in hindsight to help with only mixing what you need when it comes to fertilizing.
soil - top 1" deep, repeat. feel weight of pot. That's a better trigger, anyway.
use more perlite or similar drainage amendment. 50/50 with higher water-capacity soil (including what came with it, so brush up on that algebra.. coco coir holds less water and need only 33% perlite, give or take afew percent won't make a difference).
if the plant is droopy after properly watering the medium, it is due to the lack of perlite (or similar)