A turret with 0 km/s tracking speed just operates like a normal un-turreted weapon, it does not have 0% CTH.
As for waste of research.... waaahhh? You can only put one laser per STO. If you want more firepower per STO you would need more guns and turrets let you do that. It is also lighter than four single STOs. Four of the Single Laser examples given below would need 1,188 Tons. The Quad Turret only needs 867. Also, HORRY SHET that range... I only have Active Strength 10 and Conventional-Tech Fire Controls 
These were thrown to together as an example, so they don't have Capacitor 3 and probably aren't terribly effective given that they are 10cm Infrared Lasers. As an aside, these should have been made Non-Combat classes, since the Non-Combat makes them harder to hit but doesn't reduce their effectiveness. The more you know. 
STO, Single Laser (10cm)
Transport Size (tons) 297 Cost 7.94 Armour 3 Hit Points 9
Annual Maintenance Cost 0.99 Resupply Cost 0
10cm C1 Infrared Laser
Range 30,000 km Tracking 1,250 km/s Damage 3 / 1 Shots 1 Rate of Fire 15
Maximum Fire Control Range 100,000km Chance to Hit at Max Range 70%
Maximum Sensor Range 1,261,564km Max Range vs Missile 113,541 km
Duranium 0.3 Boronide 3.3 Vendarite 0.24 Uridium 3 Corundium 1
Development Cost 79
STO, Quad Laser (10cm)
Transport Size (tons) 867 Cost 22.04 Armour 3 Hit Points 9
Annual Maintenance Cost 2.8 Resupply Cost 0
Quad 10cm C1 Infrared Laser Turret
Range 30,000 km Tracking 1,250 km/s Damage 3 / 1 Shots 4 Rate of Fire 15
Maximum Fire Control Range 100,000km Chance to Hit at Max Range 70%
Maximum Sensor Range 1,261,564km Max Range vs Missile 113,541 km
Duranium 1.2 Boronide 13.2 Vendarite 0.24 Uridium 3 Corundium 4
Development Cost 220
I misremembered. Tracking speed 1 turrets are the useless ones. Thank you for the correction.
Let me see if I'm reading this right:
In the example there is a 321 ton savings for the quad system vs 4 of the single. Dividing by three gives us 107 tons per weapon in savings.
STOs always use a 100 ton FC*. The example indicates a starting tech FC. That leaves us with 7 tons for a sensor and a reactor.
Magnetic Confinement Fusion with 100% boost gives us 1 Power in exactly 7 tons. Without boost requires a Gas-core Anti-matter reactor. Neither of these options leave room for the sensor, so the reactor must be higher tech than this. A Vacuum Energy Power Plant with 100% boost gives us 1.2 power in exactly 3 tons. Reducing it to 2.5 tons would only give 0.9 power.
The active is an almost** perfect match for a 5 ton starting tech sensor, but that would only leave 2 tons for the reactor which isn't enough. If the active sensor is reduced to 4 tons and then given a 25% effective size bonus like the FC, that would leave exactly 3 tons for a legal reactor.
*1x range/4x speed for PD and 4x range/1x speed for anti-ship, with a (IIRC) 25% range bonus.
**There is an unexplained 1 km discrepancy in the displayed maximum sensor range, suggesting that it isn't quite the same sensor.
If I understand correctly the formula, that was quoted above - the most effective police strength force will be not one big formation, but on the contrary a stack of small formations:
4t = 2*2t
SQRT(4) = 2 < ~2.8 = 2*SQRT(2)
I understood it to mean the size of the individual elements, meaning that infantry are more effective than tanks on a ton-for-ton basis.
