The 90-second rule

Every medium has a clock. A poster has the three seconds it takes to walk past it. A cinema spot has thirty. A queue at a stand has however long the person at the front decides to take. When we designed the Manifest Mirror session, we had to choose a number, publish it, and build everything else around it. The number is ninety seconds.

It is a default rather than a law. Session length is set centrally, and a venue can change it for the whole fleet in one place. But ninety is the number we keep returning to, because it is the shortest session that still contains a whole story and the longest one a queue forgives.

Long enough to become three people

Watch a first-time guest and the session divides itself. The opening seconds go to recognition. The person in the mirror moves when they move, blinks when they blink, and is unmistakably them — wearing something they have never owned, standing somewhere they have never been. Nothing here can be hurried. Recognition is the product.

Then comes composure. Shoulders drop, the chin lifts, and the guest starts to perform for the mirror instead of testing it. That is the footage worth keeping.

Then comes the second thought: what else is in here? Switching moment is one tap on the phone, and a brand world holds ten of them. Three moments is the comfortable count inside ninety seconds — enough for a guest to discover that the world has range, not so many that each one becomes a glance.

Recognition, composure, three moments and a recording. Ninety seconds holds all four. Sixty rarely does.

Short enough that the queue moves

The mirror stands where people are already moving: a shop window, a hotel lobby, an aisle at a trade fair, the hour before a screening. The moment a session becomes open-ended, the queue stops being an attraction and becomes a risk, and the floor staff spend their evening apologising to the back of it.

A fixed session turns the mirror into something a floor manager can plan. Ninety seconds plus changeover is a unit, and units can be multiplied across an opening night, a matchday or a four-day fair. Guests read it the same way. A visible, finite session is one people are willing to wait for, because they can see it ending.

Ninety seconds is not a limit on the guest. It is a promise to everyone standing behind them.

The phone is what makes it fit

None of this would work if the guest had to make choices on the mirror itself. Touching a mirror in public is awkward, and a guest reaching for a control is a guest who has stopped looking at themselves.

So the phone becomes the remote. Pairing is a QR code: the mirror shows it, the camera reads it, qr.manifestmirror.com opens in the browser, and the session is in the guest's hand. Outfits and moments change from there while the eyes stay on the glass. Afterwards the recording arrives by email, so the guest never has to break the moment to keep it.

That division of labour is why ninety seconds feels generous rather than tight. The interface costs almost nothing. The whole budget goes to the experience.

Time is also the cost

Real-time generative video is spent in seconds of compute, not in impressions. A session with no end is a cost with no end. Fixing the session fixes the cost of a guest, and a venue with a fixed cost per guest can do the arithmetic that every other medium demands — before the campaign rather than after it.

That is the unglamorous reason the number is published instead of hidden. Partners plan with it.

What a venue actually controls

Session length is one setting among several, and it belongs to the fleet rather than to a single unit. Beside it sit the brand world and its moments, the UI look, the mirror format, and the mode: outfit only, which keeps the real room behind the guest, or full world, which replaces it.

Those choices shape the ninety seconds more than the seconds themselves do. A boutique running private appointments will lengthen the session and quieten the room. A trade-show stand at peak hour will shorten it and let the ambient loop carry the noise. A museum will leave it at ninety and let families come back twice.

The rule behind the rule

Ninety seconds is not sacred. What is sacred is that the guest leaves with something before the brand asks for anything: a recording of themselves, in a world, still looking like themselves. The session length is simply the shortest honest container for that exchange.

Get the container right and everything downstream becomes easier — the queue, the cost, the staffing, and the email that lands an hour later and gets passed across a dinner table. That is the entire argument for the number.