Yields on any concentrate or extract are MOSTLY impacted by the starting material. Different strains have different types of resin. Some plants produce a greasy resin, some its sticky, and some are kind of sandy feeling. If you are solvent washing then it wouldn't matter much, but I'm certain that with pressing it would make a big difference. There are some good rosin pressing groups on facebook with tons of info and tech.
The overall quantity and size of trichomes will also impact how much actual oil is in them to be extracted. Many sativa plants have lots of small trichomes that likely carry smaller amounts of oil in them than the huge bulbous indica trichomes. Real "Hash Plants" have been bred to barely produce any buds, but all the plant material on the them will be covered in huge trichomes just waiting to get turned into dry sift in traditional places.