Because it happens in email. Three months later the question is whether they approved this or the earlier draft, and the answer is somewhere in a thread with four people copied.
A deliverable approval is a client's recorded sign-off against a specific version of a specific deliverable.
The deliverable is uploaded with a version. The client approves, requests changes or rejects, and the decision attaches to that version with a timestamp and a name.
A client approves version three after two rounds. The record shows all three versions, the comments on each, and which one was signed — so a later dispute reads the record rather than the inbox.
It will not stop a client changing their mind. It makes clear what was agreed and when, so the change is a change rather than a disagreement about history.
Approval can complete a milestone, which releases the billing for it in Books, and closes the waiting-on-client state in the plan.
Yes, per milestone, so the invoice waits for the sign-off.
All named approvers must respond; the deliverable stays open until they do.
Yes, so feedback stays attached to what it was about.
Fourteen days, every module, no card. Or half an hour with someone who will run it on your own records and tell you where it does not help.