In this Data Insights series we’re diving deep into data from over 115,000 supply jobs booked through our platform to reveal data-driven best practices, trends, and insights that empower you to provide and run a first-rate supply service to support your schools. Stay tuned for actionable analyses and strategies drawn from real-world booking data and set your organisation up for success on supply.

When schools book supply teachers, most assume they’re drawing from a unique pool of workers. Each school feels like they have “their” supply teachers, the familiar faces who know their systems and understand their needs. But analysing years of deployment data across multiple markets reveals something surprising: your supply teachers are working across far more schools than anyone realises.

We call this the “shared worker” metric and it reveals hidden patterns about how supply teaching really works.

A shared worker is simply a supply teacher who works at multiple schools within the same local area over a given time period. It’s straightforward but what does it actually mean?

When we analysed deployment patterns across various markets over 4 years of data, we discovered enormous variation in how much worker sharing actually occurs.

The numbers vary dramatically by area:

• Rural areas: As few as 0.4 shared workers per school pair
• Densely populated urban areas: Up to 29 shared workers per school pair
• Most areas fall somewhere between 3-18 shared workers per school pair

The shared worker count measures several market behaviours simultaneously:

School Booking Patterns & Competitiveness

High sharing rates indicate schools are booking reactively and competitively. When multiple schools need cover on the same days, workers end up bouncing between them throughout the term. Low sharing suggests more strategic booking or less competition for the same time slots.

Worker Mobility and Preferences

Some workers actively seek variety and will travel between multiple schools. Others prefer to build relationships with fewer schools and work longer placements. The shared worker metric captures this behaviour at market level.

Geographic and Practical Constraints

Physical distance plays a huge role. Urban areas with schools 10 minutes apart naturally enable more sharing than rural areas where schools can be 20+ miles apart. But even within similar geographies, sharing rates vary dramatically.

The Scale of Interconnectedness

While schools might be notionally aware that their regular teachers work elsewhere, the data reveals the true extent of market interconnectedness. In urban settings, any two schools can share up to 29 workers, while in rural areas they might share less than 1 worker on average.

In urban or “high-sharing” markets, a supply teacher you consider “yours” might actually work at 10+ different schools throughout the year. That familiar face who knows your systems? They probably know 10 other school systems just as well.

This means schools in urban areas aren’t just occasionally competing, they’re systematically drawing from the same small pool, creating a level of interconnectedness that individual booking experiences don’t reveal. This effect is compounded within MATs, with member schools who benefit from some shared central services being left competing over decentralised supply.

Even in large urban areas with hundreds of supply teachers, the data consistently shows that a small core group does the majority of the work. These workers aren’t just moving between schools randomly, they’re the backbone of multiple schools’ staffing solutions simultaneously.

Understanding shared worker patterns helps explain why supply booking can feel unpredictable, why certain workers seem impossible to book, and why your “reliable” supply teachers sometimes aren’t available when you need them.

What’s particularly interesting: Even when schools plan their absences well in advance (as our previous analysis showed 87% do), they’re often planning in isolation. This creates situations where multiple schools compete for the same teachers on the same days, despite often knowing their requirements weeks ahead.

The shared worker metric reveals the true structure of your local supply market. Whether you’re running a supply service or regularly booking supply staff, understanding these patterns can help shape your temporary staffing strategy.

For MAT Central Teams: If you’re building a Preferred Supplier List it’s important to consider the nature of your Trust. Are your schools clustered together or spread apart? Are your school communities predominantly rural or urban? These considerations will help determine how to structure your lots, what supplier quality criteria to consider and which agencies to engage with.

Furthermore it’s important to understand not only which agencies your schools are using but to encourage your schools to communicate with each other, detailing exactly which staff they use and to plan effectively. This will increase the quality of cover across your Trust.

For School Leaders: Understanding this pattern helps explain why certain teachers seem impossible to book on specific days: they’re managing relationships and commitments across multiple schools.

This insight should inform our supply staffing strategy: make sure you plan ahead as much as possible and book early, and actively communicate with other local school leaders to coordinate your efforts.

Why stoke competition in this space, where we try to collaborate in so many other areas of school life?

For Supply Providers: The data reveals the complex web of relationships that quality teachers navigate. Your “exclusive” teachers aren’t exclusive – they’re working for competitors too, but this isn’t a bad thing. Identifying which teachers are working across multiple locations is the quickest way to expand your serviceable market, but make sure you’re offering the best service in the area.

For Supply Teachers: Make sure to build connections and establish your reputation with school leaders and reliable consultants. Working actively to build a network with these people is the best way to ensure you regularly receive work in the catchment area that suits you.

Your local supply teaching market operates with varying degrees of interconnectedness that most organisations have limited visibility into. The shared worker patterns reveal market dynamics that individual booking relationships don’t show.

Organisations that understand these market dynamics are better positioned to develop strategies that work with, rather than against, these underlying patterns. Whether that means redesigning PSLs (for MATs), communicating with each other about available supply staff (for individual schools), or re-thinking local branch geographies (for agencies and suppliers), the data suggests significant opportunities exist for those who recognise how the system actually works.

This analysis is based on comprehensive supply teaching deployment data spanning multiple years and markets, revealing patterns that individual schools and agencies rarely see across the full market landscape.

Our ongoing Data Insights series will continue to offer valuable perspectives and practical guidance to help schools master absence management. Keep an eye on our blog to stay informed!