There is no shoot_full command. It's just a button name for press/release/click for use whenever shoot() doesn't allow the control you need.
In short, when shoot() does what you need, you should use shoot(). When it doesn't, you need to splice the shoot() command open by emulating button presses with press/release/click commands. Common examples of requiring this would be:
- to adjust propcase values (e.g. when set_tv type commands fail or confuse you or just aren't available for what you do) after exposure and focus are done, but before you shoot,
- not to release the shutter between shots (e.g. in order not to lose focus), and
- fast react motion detect spends most of its time with shutter half pressed, looking that the LCD. It full-presses the shutter when it's ready to do so (actually the MD command may do that for the script instead, but you get the idea).