He will work long hours with no breaks apart from mealtimes and be aware that the work he does could have a significant effect on the career of someone he'd never met before. But, despite the pressures, he will return to his own school refreshed and professionally stimulated. He will also have added to his network of colleagues around the country.
When Robert talks to heads in his area about this work, they're often surprised he has the energy or can afford the time. "I've got enough to do looking after my own place, " they say. Robert's view is that he works better back at school precisely because he's got away from it for a while.
This is a view shared by Alan who does occasional consultancy work for schools outside his area and, about three times a year, runs courses for aspiring head- teachers. "It helps to keep me on my toes and stops me going stale," he says.
Apart from what individual heads (and sometimes deputies) get from working outside their institutions, there is also the benefit other senior managers and their schools gain from the experience and insights on offer.
"Often, " says Alan, "you can save people from reinventing the wheel or help them to do it better or more easily."
Heads and deputies should not underestimate the value of their skills and experience to others - both inside and outside education. Anyone involved in running a major enterprise such as a school gains both knowledge and understanding which others can use.
Too many, however, concentrate their time and energies solely on their own institution and miss the important opportunities for professional stimulation which come from working with others.
This trend has been reinforced by the pressure of change in recent years and the emphasis on competition and management. One important but underestimated effect of the changes heads have had to cope with in recent years has been to make them more inward-looking. Concentration on their own institution, particularly where it faces stiff competition for pupils and, therefore, finance, has given heads too little time and energy to participate in other professionally stimulating activities. This often applies even more to deputies.
While understandable, it has a cost - both to the individual and the school. Senior managers who take little opportunity to see what's happening beyond their particular patch become insular and have to rely on the media or the plethora of official documents to get any idea of what is happening in the world outside.
Even those who conscientiously attend meetings arranged by the local authority or their own professional groups usually focus only on local needs or their own interpretations of national issues. They pay little attention to developing skills.
Increasingly, however, heads and deputies should be seeking opportunit ies to work beyond their own immediate boundaries. As well as benefiting the individual and school, the idea of senior managers offering their skills and experience to others reinforces the important concept of an education service.
There are many opportunities - including inspection - and the advent of the new national professional qualification for headteachers will increase the scope. Training organisations are keen to recruit to their part-time teams, heads who are in post and therefore likely to have good credibility with their peers. Governors who are reluctant to have their head out of school may be persuaded by the fees that can accrue to the school budget.
For any head who is contemplating early retirement in the next few years, building up some outside work may also be an insurance against inactivity when the full-time job ends.
Mike Fielding is principal of The Community College, Chulmleigh, north Devon.