yield is dependent on so many factors of pressing.. the density and humidity of the flower matter, temps matter, amount of pressure, time of pressure, and of coarse the ol' catchall we use: genetics matter!!!!
most non growers never own a press, it eats flower up faster than anyone can smoke it.
smaller batches tend to give me the best return but also take more time in the end for the amount.
a pro tip is before you put the boots to it let it sit for almost a minute to get hot before pressing on.. so bring the plates tight, but don't feel stop pressure yet and let it sit there to warm up. i have a 40 second pre timer just so i don't rush it, longer won't hurt ya.. gets the contents fully warmed first then slowy apply pressure... slowly!!!
to much pressure and heat will leave you with dark reclaim tasting product. the goal is as light of a color as you can. if your product ends up to loose and runny that is usually to much pressure. your goal is a sticky taffy consistency. makes it very easy to pull off the paper and use that way.
pre presses and bags are great tools to use. i mainly only use a pre press when i'm not using a bag. bags are pricey but you can stuff way more in a smaller area and process more volume quicker. blowouts are the downside of it. you'll learn what bags can take how much pressure as you use them.