I always start with a fresh load everyday when I hunt. When I come in from the woods, I dump my load into my shooting berm, run a few patches soaked with rubbing alchohol, a pipe cleaner thru the touch hole, a few dry patches, and I'm ready to go in the morning. I have and use a CO2 discharger when I hunt in other locals where I can't shoot it back at camp or the truck. But my findings is that this method does not remove the entire powder charge that has been compressed in the bore, thus when you reload in the morning, you have a hotter charge in the gun from the leftover powder still in the bore from the last nights hunt. Again, these are my findings, and may not be the case for everyone else using a CO2 discharger. If I do use this method, I will run my breech scraper down the bore to loosen the powder compressed into the corners of the breech, and clean by using several alcohol patches. This is where I find the leftover powder. It may only be 5 grs, but it's enough sometimes that it can change the accuracy of my rifle.
Again, like everything else, it's personal preference.