I've been stuffing powder in cases since the 70's. I used to run through a lot of rounds shooting pistol Silhouettes, never noticed anything I recall from from one lot to another, but it's been quite a few years back.
Same with my hunting rounds. Maybe if I was shooting bench rest I might be able to notice. I've loaded from 223 to 416 Rigby and in between.
Temperature, now that's a different story. Some hard lessons can be learned shooting top of the chart in August under that hot metal roof at American shooting in Houston Texas. What you can get a way with bear hunting in Alaska may not work in South Texas.