Hi . welcome to the forum. there may be other forums or threads around that have better answers than mine....

i struggle with this same question. my father who is an excellent gardener and has been gardening for decades always says i should water the DAY BEFORE my plants start to wilt.... Ha! as if i can predict that. It also depends on soil type, how deeply your plants' root systems go and whether or not you are using mulch. basically just guess and then learn by experience.

i suppose you could look up the gallons per hour per foot of soaker hose and time it to give your beds an inch of water per week. either in one deep dose or two 1/2 inch doses.

7.5 gallons is one cubic foot of water. one cubic foot of water is one inch over 12 square feet. so your cubic feet times 12 is how many feet you can cover with an inch of water each hour.

so, say your soaker hose emits 1 gallon per hour per linear foot. you have 24 feet of it in a 4x8 bed. 24 gallons per hour, 36 square feet. so: 24 divided by 7.5 times 12 is 38.4 that is how many square feet will get a gallon of water in an hour. you only have 32. so 32/38.4 is .833; .833 hours is exactly 50 minutes. in THIS example. you'll have to re-work it for your case. or post your numbers and i will do it for you.

i have done the math for my beds and drip system. its nice to know how long i have to water to give my beds an inch of water. but when it comes to how often i run it, i am actually using my fathers more intuitive approach. sure. sometimes i wait too long. sure, sometimes i water too much. but i feel like i am learning as i go and paying better attention to my plants. and that is good.

-Jon