In the US professors enjoy the support of administrative assistants who help them work more efficiently by doing some of their tasks for them. In France administrative support is low, and the general attitude is that people manage by themselves and only go to the department administrative support when they stumble onto a block and there is something that they cannot do by themselves.
Here in the US, when I do specific tasks for the department (such as PhD admissions or recruiting), I have lots of precious help from the department administrative staff. But I am thinking about the many day-to-day tasks that go with being a professor, mostly having to do with my individual work, not with department service. For those tasks, what do theoreticians use their staff help for?
For example, does everybody other than me use them to book their travels? I feel funny having my assistant choose the time and cost of my tickets, or the tradeoff location/cost of lodging, so I do it myself, but even the simplest travel takes at least a couple of hours to arrange, I have found.
Does anyone use them to manage email? There is a mix of personal and general content of emails to me, and I find it hard to imagine my assistant dealing with it, so a different approach to email might be required. Does anyone use them for journal editor work or NSF panel work or conference program committee work? for advising students? For setting up visits? In all those cases, although a significant fraction of my time is spent doing things that could in principle be delegated ("How do I download those papers?" "What are the degree requirements for a Master's, track 2?" "Will this particular course be taught next year?", etc), they are inextricably intertwined with questions that are impossible to delegate, and I do not know how to separate the two. As a result, I am really not using my administrative help hardly at all for matters other than department committee service.
How do other people do it?