A minimum-spacing rule sets the output density rather than bounding it

Fact

Place items greedily from a candidate stream, rejecting any that falls within gap of one already placed, and the result converges on 1/gap items per unit wherever candidates are dense. The constraint does not limit density to something below the source's — it replaces the source's density with its own.

So a spacing rule tuned to "the closest two items a player can handle" produces that worst case continuously, everywhere the candidates allow it, instead of only at the peaks the source actually had.

Why it matters

The tuning knob reads backwards. Widening the gap to make the output easier also strips the sparse passages, because the same rule is the only thing deciding both; narrowing it to keep detail saturates everything. Nothing in the output carries the shape of the input any more, which is usually the reason the input was chosen as the source.

It hides whenever the candidate stream is sparse — a melody with rests looks fine — and appears the moment a continuous source is added to fill the gaps, which is exactly the change intended to make the output more even.

How to apply

• Separate the two constraints. Keep the pairwise gap for what the hands or eyes can physically separate, and add a rolling-window cap — count what is already placed in [t-w, t+w] and reject past a budget — for how much is sustainable.
• Place candidates in priority order, whole source first, so the density budget is spent on the signal and only the remainder goes to filler.
• Measure the result as a distribution, not a total: peak per window and longest empty run say what a mean rate cannot.