It's time consuming . Planning takes time. Design takes time. Reviews take time. Revisions take time.
Maintenance takes time.
Responding to the requests that come in from the web site takes time. Creating the new materials needed to put up on the web site regularly takes time. It's going to take much more time than you can imagine in the beginning. Programs have bugs and software iterations make sweeping changes that can affect other programs you use. Someone with technical knowledge needs to be on call or on retainer or on staff in order to deal with the technical matters no one else can handle or advise the firm on.