They're a big deal. Super simple, adds lots of casual richness to your loops. Took years to arrive on Octatrack.
Turn on conditionality by holding a trig button, pressing left (or right) and then rotating the level knob. Conditionality includes a number of logical ideas like "fill", probabilistic triggering with "x%", and euclidean timing with "n:m".
But what's the point?The short story is that it's way, way too easy with a looper box like Octatrack to build a pretty boring loop. Even if the musical content is interesting, our ears will get tired of the repetition. With conditional trigs, you can just pick a few key elements and add conditionality to them and suddenly the loop and repetition is broken. It feels more human.
Solid techniques involve conditionally adding some syncopated bass drum hits (or sometimes dropping a bass drum once every ~8 bars) or having an 8 bar loop trigger every 4 bars... probably. This means that you'll get accustomed to the first half of the loop but from time to time, controlled by the trig condition, you'll hear that second half.
The long story is that with conditional trigs the sequencer becomes unbounded. It's no longer a fixed, repeating pattern but instead a logical computer which unravels long, complex sequences on the fly. Almost immediately you'll begin hearing sequences that will, essentially, never repeat. In this way, it's similar to some of the generative magic of modular such as shift-registers, logic gated sequencers, euclidean patterns, and sequential switches but all laid out at your fingertips.
These techniques are better than completely random techniques like sampling-and-holding noise signals in that they're complex, long-running sequences which are reasonably self-similar. You get musical content that feels like a variation on a theme instead of mere harmonically related nonsense. Further, you can ride atop this endlessly with only slight tweaks as each change is compounded by the conditionality.
It's a lot of power in simple guise.