There is almost no discussion about the relative merits of steps and ramps in session design. So here goes.
First, definitions. A ramp transitions from one value to another in the finest steps permitted by the resolution of the medium. Steps are the same except that they progress through discrete levels at measurable and controllable intervals.
The first matter of significance is that entraining beats cannot be formed during a ramp. Why? Because each beat is spaced differently. With steps there are periods where the beat is correctly isochronic (equally spaced, applying equally to entrainable monaural or binaural beats). How long it takes for an isochronic beat to elicit entrainment-like responses is debatable. Seems to me that there is a better chance of following a rise or fall in beat frequency with even 5-10 second steps. This is more usually considered in terms of how long a beat must be maintained before the effect of the target state may begin to be felt (5+ minutes).
The second matter of significance arises when designing light tracks. LED brightness is hard to control in a linear manner. Under most circumstances this is of little concern, but when viewing subtle colour shifts in a darkened room with the LEDs millimetres from the eyeballs, ramps tend to flicker and smear whereas steps provide clear, clean, discrete colours at each step. The idiosyncrasies are exploitable.
Ramped pitches usually sound better than steps, although steps provide excellent “callbacks” to the session, conspicuous but not particularly stimulating.
I can’t think of any other AVS stimulus settings care much one way or the other. It’s good to keep the choice in mind though – the difference in effect can be quite spectacular. Being honest, most of the stuff that makes up an AVS session is fluff with no direct cause/effect or researched significance – incorporated only for interest, amusement, aesthetics and/or personal belief in its meaning.
Of course, it’s not always possible to choose between ramp and step. And then there is the question of whether raw entrainment is of great significance for the bulk of AVS applications anyway.
As always, have fun.