The way I see it, as long as it works and doesn't collapse when there's grass / crops on top, it's correct.
I recently made a dedicated raised 9x13 platform in survival using just wood for the top and concrete pillars. The pillars were:
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The whole thing collapsed when I added the dirt on top. It seemed to hold all the weight of the dirt until grass started to grow on top of it which I hadn't thought of at the time. Irritated me so much. So my next build, I used metal trussing to each pillar in both directions, then had the wood layer on top of that. Seems to be holding everything just fine now. But talk about an expensive lesson to be learned. "Don't skimp on the materials, cuz dirt is heavy and offers no structural support.
1 support isn't gonna do it. My roof top farm has several and main walls . You have a book on a tooth pick. Watch my show it shows my whole base maybe you can grab ideas. Subscribe too . http://Www.Youtube.Com/user/MsBennification