15 minute cycle is 1/12 the amount of the daily cycle for supplies. 24 hour is always motivated, I doubt you can get many motivations on a 15 minute cycle, but we'll assume 50%.. If you run 10 supply buildings, you get 40 uses in the 15 minute cycle, 24 hour cycle all 10 are boosted. To simplify, let's say assume LoA is 100% boost.
Time for fun with math!
10 buildings at 24 hour productions get tripled from motivation and LoA, the equivalent of running 30 24 hour productions.
30 24 hour productions = 360 15 minute productions. 9 hours with 10 buildings.
40 are doubled from LoA. We assumed 50% are motivated (180 motivations!) so that's 220 free 15 minute productions.
So you need to run about 140 15 minute productions, with 10 buildings, that's 14 per building per day, that's 3.5 hours nursing the game. Of course with a more realistic 20% motivation you are at 40+72=112. 360-112 = 248, or 24 productions per building = 6 hours.
So, no. 15 minute cycles are not as productive as 1 day production. Unless ya got 4-8 hours per day to watch? I suspect the same analysis with 1, 4, 8 hour production cycles will show the 8 hour is the best.
Note the amount of times buildings get motivated is the key.
Done at !;30 in the AM for me, maths and/or assumptions could be way off, so do not take this as gospel, double check please.