Thanks, that's the detail I was most hoping someone would pick up on.

It started as a flat interval and felt terrible. Every word got the same slot, so sentences never landed and it read like a stock ticker.

Now there's a base duration from the WPM setting, with per word multipliers on top: 3x on sentence-ending punctuation, 2x on commas and semicolons, and an extra 0.7x if the word is 8 characters or longer.

The punctuation weights came from reading passages out loud and noticing where I actually stopped. Those are the breath points, so giving them proportionally more time puts the sentence structure back in. The long word bump is closer to the eye tracking literature, where fixation duration scales with word length. It felt wrong for a 12 letter word to get the same slot as "the".

The actual numbers were tuned by ear over a lot of real reading. I tried syllable estimates and word frequency weighting too, but neither was noticeably better than punctuation plus length, and they made the rhythm less predictable, which turned out to matter more than being clever.