A framing for how a global vignette should function: applied last among global edits, subtle enough that "you shouldn't notice its impact until it's removed." The tool is judged to be working correctly precisely when the viewer can't consciously perceive it — its job is to quietly pull the eye back toward the center/subject, not to visibly darken the frame edges.
Practically: nudge the Effects-panel vignette slightly negative (roughly -10 to -20) rather than the heavier settings used for a stylistic vignette look. Pairs with Subject Glow via Foreground-to-Transparent Radial Gradient + Inverted Mask's inverted-mask darkening — both push attention toward the subject via imperceptible surrounding-darkening, just at different scales (whole-frame edge falloff vs. a large soft-edged region around the light source).
iPhone Portrait Mode workflow — In the iPhone Photos app's portrait editor, vignette is applied deliberately last, after lighting and depth-of-field adjustments, at a light setting (~50%) explicitly framed as a finishing touch: "you shouldn't notice it until it's removed." This reinforces the rule that vignette strength should stay just under the threshold of conscious detection. See iPhone Photos App Portrait Mode Editing Controls.
In Apple's Photos app (Edit > Adjustments), Vignette is a slider recommended to start around 25 — subtle enough to be 'barely noticeable' rather than an obvious dark frame, confirming the core claim of this concept. The presenter's own framing matches it directly: the point is to pull 'the average person's' eye toward the center of the frame without the viewer consciously registering the darkening ('The key here with the vignette is to do it so subtly that you barely notice it'). Workflow tip: toggle before/after by tapping the screen to confirm the effect stays subliminal rather than becoming an obvious dark border. Used in the same editing pass as iPhone Photos App Sharpness vs Definition (Micro-Contrast Editing) and Noise Reduction via Light-Information Density (iPhone Photos App).
Confirmed by a second source (a Lightroom Mobile Effects-tab tutorial): the Vignette slider's mechanical effect is only edge-darkening, but its real purpose is directing the viewer's eye toward the photo's focal point — framed there as 'one of the most under-utilized and yet most powerful tools' in the app. The presenter's practical test for a well-applied vignette is its own invisibility: subtle enough that removing it, not applying it, is what reveals the effect ('I really want to be subtle about this so when it's removed, that's the only time you actually see that it's been applied'). Demoed value: -15 (mild negative) on a landscape photo, applied after the other Effects-tab detail sliders — see Texture vs Clarity vs Dehaze (Lightroom Mobile Effects Sliders) — and before Color Grading/Contrast in the edit order.