You refresh the page at just the right moment, a slot appears, you click... and it's already gone. It's not just an impression: it's the normal mechanics of préfecture appointment sites. Rather than giving you practical tips (that's the role of our article on no préfecture slot available), here we explain transparently what's actually happening technically, and what Perfecture actually observes.
Slots published in batches, not continuously
Many préfectures observed by Perfecture publish availability in batches or on an irregular schedule, rather than as a continuous stream. The standard pattern is to publish a batch of slots at regular intervals — often at the start of the month, sometimes weekly, depending on the préfecture and the process. Between two publications, the calendar shows "no slot available", and that's normal: there simply isn't anything new to book.
The number of slots published per batch depends on how many staff are available at the counter for that period. For high-demand processes (residence permit, naturalisation, driving test), that number is often far below demand.
An extremely short lifespan
Once published, slots are booked first-come, first-served, directly on the official site. That's where the speed of disappearance becomes dramatic: hundreds of people refresh the same page at the same moment, for a number of spots that sometimes only reaches the dozens. The number of slots available can be limited, and several users may try to book at the same moment.
Perfecture observation
This figure is a global median, not an average: it comes from the continuous scan Perfecture runs on official préfecture sites, every 5 minutes, over a rolling 90-day window, across 750+ processes spread over roughly 200 préfectures, excluding slot re-openings. It gives a concrete measure of something many users feel without being able to put a number on: the time between a batch of slots opening and disappearing entirely.
The most contested processes
Not every process faces the same pressure. Slots for a first residence permit application, naturalisation, or a driving licence medical visit/board are among the most contested, because they combine strong structural demand with a limited number of spots per session. Conversely, some less publicised or less frequent processes are sometimes booked without much trouble, even in densely populated departments. The name of your process often matters more than the size of your préfecture when anticipating how hard it will be.
Biases that make it feel even more impossible
A few concrete factors explain why searching for a slot feels even more discouraging than it already is:
- The lag between display and reality: some sites take a few seconds to refresh the calendar's actual state after a booking, which gives the misleading impression that a slot is still available when it was just taken.
- Load spikes: at the exact moment a batch opens, the préfecture's site can slow down under the surge of simultaneous connections, which lengthens the time it takes to click at the worst possible moment.
- Repeated failure: coming back several times a day without success reinforces the feeling that "it never opens", when in fact the opening sometimes happened at a time you weren't connected.
Why refreshing by hand isn't enough
Manually refreshing a page every few minutes is like playing a lottery where the window sometimes only lasts seconds. Even being at your screen at the right moment, the time it takes to click, fill in the booking form and confirm can be enough for the slot to be taken by someone else. It's frustrating, but it's not a bug on the préfecture's site: it's the direct consequence of an appointment supply well below demand for some processes and some areas.
What Perfecture actually does
Perfecture scans official préfecture sites every 5 minutes for the process you're tracking, and sends you an alert (email, browser push notification, or Telegram, depending on your setup) as soon as a slot is detected. The booking link always points to the official site: the booking itself always happens there, never through Perfecture. No booking is guaranteed — being alerted shortens the delay between detection and your being informed, without guaranteeing the slot will still be available.
Perfecture is an independent service, not affiliated with the administration.
Watch the mechanics live
To see the rhythm of slots opening and closing in your department first-hand, check our live map, organised by process and by department.
What still needs clarifying
- The median slot lifespan varies a lot by process and préfecture: the figure above is a global median, not a local guarantee.
- The pace at which batches are published (weekly, monthly, irregular) isn't documented officially by any préfecture; it can only be inferred through observation over time.
- Internal Perfecture data (scan of official préfecture sites, every 5 minutes)