Of course it all depends on the given perspective, but in SFC it's concentration of firepower that matters. In almost every circumstance, with heavy weapons you'd be better off if all of the torps were aiming in the same direction. Typically forward. Phasers are different because they are used for point defense as well. Which brings the one reason for dividing your firepower up, if you can be outmaneuvered by your enemy so you can't bring them into you concentrated firing arc. That's why, in SFC, it's the really large and unmaneuverable ships that have rear firing torps, generally BBs and Tugs.
There are racial exceptions. The Gorn and ISC, but they are seeking weapons and their ships, by and large, are less maneuverable. The ISC were also designed to fight in the Echelon Formation.
The ships that were added as canon ships (the Miranda for example) that have their torps divided between the front and rear get easily outclassed by comparable ships (the NCA in the instance of the Miranda) that concentrate their firepower in one direction.
In reality the ships in Trek would be armed more like wet navy ships, not fighters, as they more or less are now. That's the obvious layout. Like the FRAX, for those of you who are familiar with them from SFB.