One Volunteer Shift or Separate Roles?
Group tasks one person can do together, and split jobs that need different people or times. Proximatic shows who's doing each one and where you still need help.
Greeting guests and handing out maps can be one job at the same desk. Driving across town for supplies cannot be part of that person's shift while they're supposed to be welcoming arrivals.
Make a shift around work one person can sensibly own. In Proximatic, put the desk tasks together under Welcome and list them in its instructions. Give Supply pickup a separate shift with the route, time and places it needs.
Now volunteers can make a useful choice. Someone who wants a public-facing job takes welcome; someone who can collect supplies takes pickup. Both commitments land on the event roster, so filling the desk doesn't hide the fact that nobody is bringing the materials.
Split work when the hours, location or required experience change who can do it. Combine tasks when separating them would only make one person book several pieces of the same job.
Create your event and roles. For more on combining small tasks, see avoiding too many tiny shifts.