Update: To be clear, I've got 3 commands, and I want 1 of the 3 to execute, effectively on loop.
I've got a couple command blocks, each with some commands, and I want them to execute at random intervals.
My strategy so far is to use chickens that wonder in a pen stepping on pressure plates, but they don't move often enough and I'd rather not just resort to duplicting commands:
I've tried a lot of ideas with the chickens, (speed effects, spawning an entity holding seeds), but I think I'll need something better.
Any ideas?

