the mad [water] dash

Two plastic watering cans - one with a larger holding capacity, the other with a bigger watering can rose - a hose pipe, and a rainwater tank with an elevated tap switch. Watering all the garden beds is a delicately timed affair. The time it takes for the second watering can to fill up is usually enough to walk to a garden bed and water the plants with the first watering can, and come back. That is, if there are no distractions (such as pruning tomatoes, looking at bugs, thinking about how to prevent more weeds, picking out weeds). But there are other factors to consider too - three other factors, to be precise. One, the water-flowing rates of the rainwater tank, can number one, and can number two are different (since one of the rose heads is bigger). Two, the water capacity of the two cans are different. Three, the distance from the water tank to each garden bed area is different. 

The outflow rate of the bigger rosed watering can is obviously higher, and because that can has a smaller capacity, it takes much less time to deplete the water. This means that, compared to the inverse situation, by the time I get back to the water tank, the larger can hasn't filled up as much yet. The bright side of this is that there is more leeway for distraction. But how much distraction is acceptable before the other watering can starts overflowing, considering also the distance and time to get from whatever part of the yard back to the water tank? 

Such is the delicate nature of watering of the garden.