I think Site Managers have the most difficult job on capital projects.
The people who do this have to multi-task constantly, many issues e.g. labour relations, programming, safe systems of work, the weather and implementation of the CDM construction phase plan.
They work long hours and most work away from home.
Very rarely did I see a job description for this role. Maybe due to many of them being self-employed, temporary staff rather than employees of the EPCM contractor.
Most incumbents came up through the trades and were not degree educated.
Even though they normally have a site team, I found that for construction success, Project Managers and Project Engineers must be encouraged to understand their role and fully support them (and take responsibility) for medium and long term planning issues.