Off topic....is it ok to store your powder in the hopper if you are only loading one type of round?
As is so often the case, the real answer is "it depends."
As others have noted, gunpowder is not completely inert. Exposure to high humidity or high temps accelerates the degradation. If you store canisters of powder somewhere dry and cool, but your press/hopper is somewhere warm and/or wet, then all the time the powder spends in the hopper (whether you're there or not) accelerates it. If, on the other hand, you store it in the same room/climate, then that's not a source of difference. So the answer depends in part on the specific climate conditions of both storage and the hopper.
How about the container versus the hopper? Are those really different? It depends. Squeeze a plastic jug of powder that you have opened at least once before (and therefore removed/broken the actual seal). You will notice that, no matter how tightly you cap the jug, most or all of them will let some air out gradually. Those plastic canisters aren't air tight (for various safety reasons). If you have a relatively snug-fitting lid for your hopper, and the hopper isn't too fat/wide, you probably don't actually get much more air flow/exposure in the hopper.
How about the materials of the hopper versus the jugs? Well, those are usually different. A subset of powders will react with
some hopper materials and etch or degrade them. So that's a potential source of difference. If you have a powder that interacts with a hopper, don't leave it in the hopper any longer than necessary! (None of the powders I use seem to interact with any of the hoppers that I use... and if they did, I'd probably not buy any more of that powder going forward, but everyone has different characteristics they prioritize in the powder purchasing.) So as to whether there is any downside to leaving the powder in the hopper from this factor, it depends on the powder and the material of the hopper.
How about the risk of not knowing what is in the hopper? Well, that depends on what your loading methods are. If you store the powder somewhere other than your bench and only ever have one powder on the bench at a time, and you keep the canister next to the hopper while the powder is in the hopper... well, that's what powder is in the hopper. If you are someone who stores powders immediately adjacent to the hopper, or who puts the empty/half-full canister back in storage while you're loading, then the potential for confusion/forgetfulness does increase as time goes on... although these don't seem like ideal practices anyway.
I wouldn't say that I disagree with those who say they don't, but I do have a different perspective. I am a competitive USPSA shooter. That means I load significant volumes of my gamer loads, and then intermittently load much smaller batches/volumes of all the other rounds I load. About 90% of the time, my press sits ready to load my gamer load, with powder in the hopper. It can stay that way for weeks at a time, with me loading rounds one day, then coming back later that week to load more, then maybe 2-3 days running, then no loading for 2 weeks. I've been doing this for several years. I only ever have one powder on the bench at a time, so I never get confused about what powder is in the hopper.... it's whatever canister is sitting on the bench (most often VV N320 these days); my powder storage is in the same dehumidified environment, but a few yards away. Cycling the hopper empty takes several minutes, usually involves a loss of a small amount of powder, etc.... I'm not doing that if I know for a fact I'll be back in a few days to load exactly the same stuff. I have been doing it this way for years and with many tens - perhaps hundreds - of thousands of rounds downrange. This approach has had no apparent adverse effect. Should
you do that? I don't know. You have to work through the logical factors as to potential sources of trouble and see what the answer is for you.