Hi - almost every task in our projects have multiple assignees. We even give each assignee different planned hours too to make sure that overall they fall into the SOW/Estimate we got approval from the client. Like for Design, the Art Director and Copywriter might be 40 hours each but the Creative Director is just 5 hours to cover reviews.
So I would definitely recommend adding everyone involved in the task to the assignments. (You can then do an Assignment report which separates all of them for reporting on a single person's work, or grouping by job role.)
Of course, if you were doing timesheets in Workfront, that is the best source, but we have found that as long as the PM is adding people and adjusting planned hours as tasks go back and forth, we get close to seeing what is really going on. In fact, we our audit of milestones for Chicago, we found that we wanted to adjust the Internal Review tasks to 1.5 hours as we looked at the average of all Internal Reviews in 2020 and the average was around 1.5 hours instead of 1 hour.
Hope that helps.