Polymeter is the cheapest way to make a loop evolve without writing more notes

Polymeter places two voices with different bar lengths over a shared pulse. A 3-step loop against a 4-step loop causes their phases to drift and realign over several bars (the LCM of the two lengths). This generates long-form variation automatically from very short loops — the two voices create new combinations at each realignment point. This makes polymeter valuable in techno, IDM, and minimalist composition where material is deliberately short but must sustain interest over long durations. The phase realignment is a structural event that can serve as an arrangement landmark.

Examples

In Strudel: {bd sd, hh hh hh}%4. The bd/sd pattern (2 steps) and the hh pattern (3 steps) diverge and re-sync every 6 beats (LCM of 2 and 3).

Assessment

Given a 3-step kick loop and a 4-step hi-hat loop at the same BPM, after how many beats do they first realign? How does this auto-generate variation without writing new notes?