I planted a few tomato and pepper plants during Memorial Day weekend from bedding plants. I used a 5-gallon bucket and 8 of our watering spikes.
I am in Ohio, so we have had more rain than in other parts of the US this summer. I have filled my 5-gallon bucket up about two times between Memorial weekend and the weekend of the 4th of July. I do not use any other water outside of rainfall and the bucket watering system.
The plants are doing great. The plants survived Brood X cicadas, who just hung out on the plants and the hoses.
Here is my favorite part - I have not had to weed my raised garden 30 days into the growing season.
Besides the low water usage, I believe a considerable benefit of using the watering spikes is the lack of weeds. The water is delivered under the soil by the water spikes, and weeds don't get a great start. See my pictures below from the weekend of the 4th. No weeding!