I like the idea of filling in the gap. Truth be told what you have will cover things pretty well. I spent many years on the quest to fill all the gaps. Currently I have .223, .243, 6.5 x 55, 7mm Rem. Mag, .308, .338 Federal, .375 H&H, 45/70, .458 Win Mag.
No, I don‘t need them all, but I like...