This is a great question, and the answer is counterintuitive. On the surface, "keep me guessing" sounds like the right answer. Yet, so many teams (in so many sports) do the opposite to incredible success. Human psychology is powerful. If a defender doesn't know what's coming, he's more reliant on scouting and reading his keys to determine the play and then execute. But, when you give a person what appears to be a pattern, like calling a play multiple times, they begin reacting to that pattern. Humans simply love to look for patterns, even if they are not there. Their reactions can become very predictable.
Case in point, those seemingly annoying screens Arky St ran last night. They're not hard to stop, it's just a numbers game. Even Nebraska eventually stopped them. They're effectiveness is in forcing you to stop them and then using complementary plays to exploit your tendency to put numbers in places you don't want them, like near the boundary where you can become isolated. I say this Arky St offense wasn't very good because they simply didn't have much to flow off of those screens.
The best offenses, regardless of what form they take, do. Running, passing, none of that really matters one way or another if plays don't cause defenders to think. Thinking makes you slow. Reading your keys, staying disciplined, and flowing to the football makes defenders fast. The defenders that seem to play that little bit faster aren't that way because they knew what was coming, but rather because they read the play and used their momentum towards making a tackle rather than think they knew the play and had it used against them.