Fashion revivals arrive on a fairly regular schedule, and the interval is long enough to be noticeable. The mechanism behind it is demographic rather than aesthetic.
The revivers were children the first time
The people with influence over what is designed, styled and bought are usually in their late twenties and thirties. A generation earlier they were young enough to absorb a look without wearing it themselves.
Childhood impressions of clothing carry emotional weight without the specific embarrassment of having personally worn the worst of it.
That combination makes a style from roughly two decades earlier attractive to revive: familiar enough to feel meaningful, distant enough to feel fresh.
The immediately preceding era is unusable
A style from five or ten years ago is not old, it is merely out of date, and reviving it reads as failing to keep up rather than as a reference.
Enough time has to pass for the association to shift from dated to historical, and that shift takes roughly the length of a generation's memory.
This is why the decade just gone is consistently the least fashionable one and why it eventually becomes among the most mined.
Revivals are selective rather than faithful
What returns is never the whole period. It is a small set of silhouettes and details filtered through how the era was later photographed and remembered.
Media images do the filtering, so the revival often reproduces what was worn on screen and on stage rather than what was worn on the street.
The revived version is also cut to contemporary proportions and made in contemporary fabrics, which is why period photographs rarely resemble the revival closely.
Archives make revival cheap for a brand
A house with a long history holds patterns, prints and hardware it already owns, and reissuing them costs far less than developing something new.
Reissues also carry a ready-made story, which reduces the marketing work needed to explain why a garment matters.
The commercial logic reinforces the demographic one, so brands lean into revivals precisely when the audience is primed to receive them.
The cycle is compressing but not disappearing
Digital archives make every era visible at once, so several periods are now referenced simultaneously rather than one at a time.
The result is shorter revivals overlapping each other instead of a single dominant retro moment lasting years.
The underlying driver is unchanged. As long as the people making decisions are working from the images that shaped them as children, the delay will roughly match the length of a career's start.