I try to mix it up. Usually a dagonfly and something else.
If your goal was to try a different combo every day though, if you have 5 knives and carry 2 at a time, you could have 10 different combos. A different one for every day of the week. 6 knives and you get 15 combos. 12 knives you get 66 combos.... 28 knives and you get 378 combos, a different combo for every day of the year!
And if you have 28 knives and carry 3 knives at a time, you could carry a different combo every day for 8 years