Do Sub Jobs Go Unfilled? Two Weeks and 34,000 Frontline Postings Later

Two weeks ago we wrote about how long sub jobs last and promised two things: a sharper look below the one-minute floor, and a closer look at what happens to the postings nobody grabs. Here is both.

The dataset has grown. This time it's about 34,000 Frontline postings across 193 districts over two full school weeks, from the last Friday of August through this Wednesday. Every posting was timestamped when it appeared on the board and again when it disappeared, and this time we also recorded each job's own start time, which is what lets us ask the new question.

Below the minute

In the last post, the finest thing we could say about a fast district was "gone in under a minute." For one week, in three of the busiest districts we watch, we recorded disappearances closely enough to say more.

The result is less dramatic than the folklore. In a large Bay Area district, one posting in twenty was gone within ten seconds. About a third were gone within thirty seconds, and roughly seven in ten within a minute. Two large Florida districts looked much the same: three percent gone within ten seconds, a bit over half within a minute.

So "gone in under a minute" mostly means twenty to sixty seconds, not five. That matters, because twenty seconds is a human number. A person who has the alert in their hand and taps within half a minute is still in the race for most of these jobs. The people who lose them are the ones who find out at lunch.

Do postings actually go unfilled?

This is the question we couldn't answer before. A posting that disappears has either been taken or has expired, and without the job's own start time you can't tell which. Now we can, at least approximately: if a posting vanishes more than two hours before its start time, someone took it. If it's still sitting there two hours before class, or at the bell, nobody did.

Across everything we tracked, 82% of postings were filled more than two hours before they started. The other 18% were still open two hours out: some got taken at the last minute, some were still on the board when the start time passed.

That number hides a split that lines up exactly with the district groups from last time:

In the fast and medium districts, roughly one posting in six goes to the wire. In the slow districts it's nearly one in three, and most of those were never seen taken at all. Hours districts are about a third of the districts we watch and about a fifth of the postings, so this is not a rounding error: a meaningful share of the sub jobs on Frontline right now will not be filled through the board.

That cuts two ways. For a sub in a slow district, the calm board last time's post described is real, and some of what's on it is genuinely still there tomorrow. For a district office, a third of postings reaching the morning of the absence unfilled is a staffing number, not a technology one, and no app fixes it.

The clock matters more than the calendar

We expected postings for far-off dates to linger and same-day emergencies to vanish. It's the other way round.

Same-day postings last longest, with a median around two minutes. The jobs that disappear fastest are the ones a week or more away: a full day, a known school, nothing surprising about the date. Those are the postings people have filters set for, and they go in seconds.

The time of day is the sharper cut. Between eight in the morning and four in the afternoon, local time, the typical posting is gone within a minute, and 82 to 90% are gone within five minutes. Postings that appear between eleven at night and six in the morning last two to three minutes at the median. That is still fast, but it's the difference between a job you can catch from the couch and one you can't.

Day of the week barely registers. Monday through Wednesday look alike; Thursday through Saturday run a little slower. (One of our two Mondays was Labor Day, so treat the Monday number as one week's worth.) We wrote about the weekly posting rhythm earlier; this is the other half of it, how long each of those postings then lasts.

The district groups, two weeks on

With 193 districts instead of 82, the split held: 38% Seconds, 27% Minutes, 35% Hours. In the fastest large districts, two thirds to nearly nine in ten postings are gone within a minute. In the slowest, more than half of postings are still open two days later.

Everything from last time still stands. District size predicts nothing. The average posting is not the posting you want. The board looking calm tells you nothing about the three jobs you'd have said yes to.

What this means for you

• If your district is fast, you're racing for seconds, not milliseconds. Twenty to sixty seconds is the window for most contested postings. An alert in your hand plus a tap beats checking, every time; auto-accept beats both.
• If your district is slow, some jobs really do wait. But the good ones don't, and one in three of the rest never gets filled at all. Set the filter for the jobs you want and let the rest sit.
• Evenings and nights are your window. A posting at 11 PM lasts minutes, not seconds. A posting at 11 AM does not.

What we can't tell you

• A minute is the finest span we quote for most districts. Our disappearance times are accurate to within about a minute nearly everywhere, and to within ten seconds only in the three districts above.
• Some disappearances are flicker. Among jobs our own users booked, about one in nine had briefly dropped off the board and come back before the booking. So the shares "gone within a minute" are a little high, by up to ten points. The ordering of districts and hours doesn't change.
• "Still open" means nobody we watch saw it taken. A job assigned by a district office off the board looks the same to us as one nobody took.
• Two weeks, one holiday. Back-to-school is in the data; so is Labor Day.
• No district names. A list of slow districts would mostly help the people racing you for them.

Where Sub Hero fits

Sub Hero watches Frontline continuously and sends a push notification the moment a posting matching your filters appears, which is what puts you inside that twenty-second window instead of finding out at lunch. On the Pro plan it can accept the job for you, typically about a second after the posting shows up. It won't fill a job nobody posted, and it can't help with the third of slow-district postings that expire on the board. What it does is make sure the handful you actually wanted didn't go by while you were teaching, driving, or asleep.

Learn more: app.getsubhero.com

Plans start at $6.99/month. Works with Frontline Absence Management.