Assigning work and seeing who did what
Give an engagement or a client an owner so the team knows whose desk it is on, and check the activity log when you need to know what happened.
Assigning
With team mode on, engagements and clients can be assigned to a person. It is not a lock, it is a label: everyone can still work on everything, but nobody wonders whose job it is.
You can reassign at any time, which is what actually happens when someone takes holiday.
Just my work
Your lists can filter to what is assigned to you, so a shared firm still gives you a personal task list.
Who did what
Team settings carry an activity record of what your team has been doing. It answers the ordinary questions: who approved that, when did this go out, who talked to this client last.
Owners also get a fuller, firm-wide audit log with filters. See the audit log.