I notice that to with the one shot, smaller cases like 222 and 243/25-06 are very easy, where as my magnums like 264/7RM/ 338 EDGE is not very easy when resizing. With the 338, its exceptionally hard. Can spray more lube but then you run into dented necks/shoulders. It says to spray from all 4 sides though at a downward angle so it gets into the neck. Usually when I size my 338s I'll get a qtip and swipe the inside neck with rcbs lube, makes it 10x easier.
I've never tried the imperial, seems like a hassle and time consuming versus spray?
I'll use a lube pad if I'm only doing 20 or so, but when I'm doing 50 or more, I'll get the one shot.
Have fun with that 500 rounds!!!