Mmm...see what you mean confusing to say the least. I have 4-5 CF boxes but non as big as that one. I reckon it will hold 900+ as they say but that's 900 small flies size 14-18 perhaps. Well if you leave a space between each fly it must hold 450 larger ones!!!
I often leave spaces between mine, looks neater and easier to get flies in and out, also simpler for quick identification. So yes I think it would be fine.
I have about a dozen CF products and always have a smile reading the literature that comes with the package. Obviously written in Japan by a man with an English dictionary in one hand.
Chris