1. Run the attached project (or use any script that shows values of deltaTime variable of Input.GetTouch) on Android device
2. Touchthe screen of the device and try not to move your finger
3. Check what value of deltaTime variable is

Actual result:
The last number of Input.GetTouch (i).deltaTime 0.00X is always changing and never is the same, although the tap is not changed.

Expected result:
Probably there is no need in such high precision because user will need to truncate this value himself