You’re conflating Watt-hours and Watts. Watts are a measure of power, which is energy consumption per unit time. Watt-hour is power multiplied by time, the time cancels and so it’s a measure of energy. 0.5 Watts for an entire day adds up to 12 Watt-hours in a day, which is a reasonable estimate for a phone battery.
The average telephone uses 4.5-11 watts of energy a day. 0.5 is barely anything, flip phones maybe used that much 20 years ago.
You’re conflating Watt-hours and Watts. Watts are a measure of power, which is energy consumption per unit time. Watt-hour is power multiplied by time, the time cancels and so it’s a measure of energy. 0.5 Watts for an entire day adds up to 12 Watt-hours in a day, which is a reasonable estimate for a phone battery.