They are experienced in most subject matter areas. They cannot perform simultaneous interpreting, but are generally competent to handle most consecutive interpreting assignments, particularly if the assignment does not include highly specialized subject matter. There is no substitute for a good briefing, as far in advance of the interpreting session as possible. It is not unusual for an interpreter to handle a biotechnology conference one day, and a financial conference the next. If you are aware of unique terms that are likely to be used, it is absolutely essential that you pass these along in advance of the session.
Interpreters are professionals who take pride in their work.
They cannot, however, be expected to know every industry term and slang expression. To the extent that you can help your interpreter prepare for your session, the more effective your interpreter will be. In turn, your conference or session will be that much more effective. Whenever possible, try to give your interpreter lists of specialized terms several days in advance. If you have materials that place these terms in context, it is enormously valuable to the interpreter to receive these as well.