Originally Posted by
Valyrian the Moofia Boss
Starfleet ship phasers can hit any critical system on any other Starfleet ship from any direction, given the saucer and nacelle design and the negative space that entails. If they were going up against a super-massive object such as Borg cube, where a single side can obscure the line of sight of the other 5 sides at once, then yes facing would be important.
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Facing in such a situation would only matter if either ship needed to launch a torpedo, and you save torpedoes for the part when the enemy shields have depleted and it's time for a finishing blow (as phasers are effective against shields and torpedoes ineffective, while phasers deal minimal damage to exposed hulls while torpedoes just blow said hulls to smithereens).