While it may seem like high THC bud = big yields, any hashmaker will tell you that’s not the whole case. No extraction process is perfect, so it’s best to think of a flower’s THC content as its maximum potential. Morphological differences between genetics, and even buds from different parts of the plant, can play a significant role in how much of that potential THC can be extracted. A looser bud structure that exposes the calyxes (think flower petals, for the less cannabis-knowledgeable) is key to allowing the resin-bearing glands, or trichomes, to be effectively separated from the green material of the flower.
Furthermore, high-THC bud without a favorable trichome structure, especially in the case of solventless concentration techniques, can yield poorly. Trichomes with longer stalks, called capitate-stalked trichomes, separate from the unwanted plant material more easily, in addition to expressing cannabinoids more abundantly. While hydrocarbon or ethanol-based extraction techniques are less influenced by these mechanical factors, speed, efficiency, and yield will still favor strains where these structural features are present.
In the end, you take the input product you can get, but high-cannabinoid, high-quality, clean, loose-flowered bud will beat everything else in essentially every process (using milled flower in hydrocarbon, ethanol, or other processes can have mixed results, but is one way around this). When it comes to this aspect of laboratory production, strong QA/QC controls at product intake and clearly defined standards regarding bud quality and potency are the biggest protection against unexpected low yields or dirty processes.
