I do mainly coco/perlite 70/30 in 3 gallon pots.
I personally recommend feeding with every watering and doing so every day. Coco naturally holds the perfect amount of water as well as air. Its essentially impossible to over water coco.. it will hold it’s max capacity of water and let the rest drain. It’s technically hydroponic so you want to keep it saturated constantly. Because even when it’s fully saturated, it is still getting plenty of oxygen.
I water with 20% at least run off every time. I use a slightly reduced feeding schedule because I am feeding every day but I believe you’ll find daily fertilization/feeding to be the common way to do it.
If you chose to the feeding every 3 days I believe your results will be inferior to daily feeding.
It’s my favorite medium and you’ll find excellent results.
Keep pH on point.. 5.6 to 6.0 is fine frankly but being consistent is best with pH