[FEATURE] Allow break duration up to 120 seconds

[c0nc3p2a11]

Summary

The break timer currently caps the pause length at 60 seconds. I'd like to propose raising the maximum to 120 seconds (keeping the current default and all shorter values unchanged). This is a one‑line change to a configuration bound, it's fully backward‑compatible, and it lets the app cover the break durations that the current peer‑reviewed evidence actually points to. Right now the 60 s ceiling makes it impossible to configure a break in the 1–2 minute range that eye‑care researchers now recommend.

Current behavior

• Break/pause duration is user‑configurable but hard‑limited to a maximum of 60 s.
• This implicitly bakes in the "20‑20‑20" model (a 20 s look‑away every 20 min), which is popular but, as shown below, has weak and largely negative evidence.

Proposed behavior

• Raise the maximum configurable break duration to 120 s.
• Keep the existing default and lower bound as they are — this only extends the allowed range, it removes nothing.

Rationale / evidence

1. The 20‑second break is not supported by evidence; the researchers suggest 1–2 minutes

The "20 seconds" figure was never derived from data — it was coined in the late 1990s as a memorable slogan. When it was actually tested, it failed to show a benefit.

• In a controlled study, participants performed a demanding 40‑minute reading task while taking 20 s breaks at 5‑, 10‑, 20‑, or 40‑minute intervals. There was no significant effect of the scheduled 20 s breaks on reported symptoms, reading speed, or task accuracy — including in the most symptomatic subgroup. Johnson S, Rosenfield M. 20‑20‑20 Rule: Are These Numbers Justified? Optom Vis Sci. 2023;100(1):52–56. https://pubmed.ncbi.nlm.nih.gov/36473088/
• The study's senior author (Mark Rosenfield) has publicly stated that his suspicion is that breaks need to be longer than 20 s — on the order of 1 to 2 minutes — with the optimal frequency still to be determined.
  A 60 s cap physically cannot reach the top of that suggested 1–2 minute range. A 120 s cap does.

2. The focusing system needs more than 20 s to relax after near work

There is a physiological reason short breaks underperform: after sustained near work, the accommodative system stays biased toward "near" and does not release instantly (accommodative adaptation / near‑work‑induced transient myopia, NITM).

• A sustained near task was shown to induce transient myopia that persisted into subsequent distance viewing (mean ≈ 0.29 D), attributed to a lingering shift in tonic accommodation and increased accommodative innervation. Near vision stress: vergence adaptation and accommodative fatigue. https://pubmed.ncbi.nlm.nih.gov/3454910/
  Because this after‑effect decays over tens of seconds to minutes rather than instantly, a longer look‑away (approaching ~90–120 s) gives the ciliary muscle a realistic margin to unwind toward baseline. A 20–60 s break often ends before that has happened.

3. The newest data favor more frequent / self‑paced breaks and don't validate a fixed 20‑second design

• A 2025 laboratory study compared four break schedules during a 40‑minute reading task (no break / one break at 20 min / a break every 10 min / self‑paced). Breaks every 10 min or self‑paced alleviated digital‑eye‑strain symptoms, kept accommodation more stable, and minimized the transient myopic shift, whereas the 20‑20‑20 rule was "not effective enough" to manage DES. Redondo B, Jiménez R, Vera J, Rosenfield M. The impact of break schedules on digital eye strain symptoms and ocular accommodation during prolonged near work. Exp Eye Res. 2025;258:110463. doi:10.1016/j.exer.2025.110463 · PubMed record: https://pubmed.ncbi.nlm.nih.gov/?term=10.1016%2Fj.exer.2025.110463
  The practical takeaway from this line of work is flexibility — letting users pace and size their own breaks rather than being locked into one short, fixed value. A wider duration range directly supports that.

4. For myopia‑relevant near‑work breaks, "brief" is explicitly flagged as too short

• A clinical perspective reviewing the animal‑model literature concluded that very brief breaks — even if frequent — are relatively ineffective for offsetting near‑work effects on eye growth, with sustained breaks of ~5 minutes being the length supported by that data. Pucker AD, Gawne TJ. Fighting Myopia with Intermittent Nearwork Breaks: 20 Seconds Every 20 Minutes Might Not Be Enough Time. Optom Vis Sci. 2023;100(1):31–32. https://pubmed.ncbi.nlm.nih.gov/36705713/
  (Note: this endpoint is myopia/eye‑growth in animal models, not DES symptoms in humans — but it points the same direction: longer breaks, not shorter. It's supporting context, not the primary argument.)

5. Individual variability argues for a higher configurable ceiling, not a fixed one

• Even where reminder‑based breaks helped, the effect was on the dry‑eye/symptom side and was not uniform, and objective signs often didn't move — underscoring that one fixed break length doesn't fit everyone. Talens‑Estarelles C, et al. The effects of breaks on digital eye strain, dry eye and binocular vision: Testing the 20‑20‑20 rule. Cont Lens Anterior Eye. 2023;46(2):101744. https://pubmed.ncbi.nlm.nih.gov/35963776/
  Symptomatic users, and those with underlying accommodative or binocular issues, plausibly need longer pauses. A configurable ceiling of 120 s lets them match their own needs and the emerging evidence at zero cost to everyone else.

Why 120 s specifically

• It comfortably covers the 1–2 minute range suggested by the researchers who actually tested the 20 s rule (point 1).
• It gives enough time for the accommodative after‑effect to substantially decay (point 2).
• It's a modest, safe increase — long enough to be useful, short enough that users won't lose their work rhythm — and it keeps every existing shorter option intact.

Scope / implementation

• Change the upper bound of the break‑duration setting from 60 s to 120 s (validation + any UI slider/stepper max).
• No change to defaults, persistence format, or existing user configs.
• Backward‑compatible: purely widens the allowed range.

Acceptance criteria

• Break duration can be set to any value up to and including 120 s.
• Existing default and all values ≤ 60 s continue to work unchanged.
• Saved/older configurations remain valid.