In digital photography, can I release the shutter immediately after pressing it completely, or press it for a while before releasing it?

Pressing the shutter has two functions. First, press the shutter to complete the focus, and then press the shutter to close completely to complete the imaging. All modes of all cameras are the same. After the shutter is fully pressed, it can be released immediately, because the exposure time is completed by the curtain inside the camera and is controlled electronically, regardless of the time the shutter is pressed.