The best way to use it for pain is just leave it on longer if you are in more pain and still put the next one on as well, in time I think that would double your dose. Double the amount of time it's worn by wearing two. I'm really stoned, that might make no sense.
It takes about a week to get into your system at the full dose from a patch. I extracted loads of bupe over the last couple of years and didn't find any great use for it, some went moldy and was binned. Left in alcohol it was preserved but fricking stings. If I needed more pain relief and plugged more bupe, or under the tongue, or rolled it on my skin mixed with perfume, mostly it made me feel sick because of my other opiates getting displaced, so I believe.