If I'm not mistaken, nearly every attack on a ship in Star Trek (usually followed by a declaration like "We're are under attack!") is followed by the captain, or another senior officer, saying one or more of these:
- Red alert! or Battle stations!,
- Shields up! or Shields to maximum power!
- anything similar or related.
A similar thing can be observed with many contacts with the Borg (especially in VOY: Scorpion). A crew member (Tom Paris?) informs the captain that they're being chased by five or more Borg cubes (where meeting just one would most likely mean assimilation or destruction) and the captain must order him to raise shields, go to red alert and start evasive manoeuvres.
Why is this so? Why does any sign of attack not imply automated shields up and automated red alert? If the survival of the ship (and its crew) is the most important part of every journey through space, then why do such procedures not happen automatically and nearly always have to be ordered?