I think the amount of water wasted will be closer to a 1 gallon measure because 1 gallon would be closer then a shower or a cup.
Based on the given information, we can estimate the amount of water wasted by the leaky faucet over the course of 1 day. The given sources provide different estimates of the amount of water wasted by a leaky faucet, ranging from 1 cup to 1 gallon or more.
According to the US Geological Survey, one gallon of water is wasted by a leaky faucet every 15,140 drips
A leaky faucet that drips once every second every day, all day, wastes 5 gallons of water per day or 2,082 gallons per year
A leaky faucet that drips at the rate of 10 drips per minute wastes 29 gallons per month
A leaky faucet that drips at the rate of one drip per second can waste more than 3,000 gallons per year
Based on these estimates, we can conclude that the amount of water wasted by the leaky faucet over the course of 1 day is closer to the estimate of 1 gallon than to the estimates of 1 cup or 1 shower.