While the new multi-select functionality is exciting and something we’ve been anticipating, I believe the current implementation is a bit lacking in utility and could be further improved.
Blockers:
  1. You cannot enter multiple email addresses into the search box and “Select All,” resulting in a very manual and repetitive process of:
a. Enter email 1
b. Select the agent
c. Remove the email
d. Copy/paste email 2
e. Select the agent
f. Remove the email
g. Repeat
While this may be manageable for small populations, it makes it very tedious to update schedules for say, an All-Hands meeting that has 50+ attendees.
2. You cannot deselect one (or multiple) agents without entering their email addresses 1-by-1 and de-selecting them (unless you want to remove all agents and start over). It would be better if, open clicking into an empty "Search Agents…” box, it would show a dropdown of all agents already selected. There could also be a button directly on the timeline, maybe next to the agent name, for a “quick remove” action.
Given these limitations, it is unlikely that I (personally) will leverage multi-select beyond very niche cases.