Time units accounted for wrong user because of multiple users working on drafts

Scenario:

1. User A creates a draft and records his time units spent.
2. User B, who is for e.g. the supervisor of the ticket reviews the draft and sends it.

In this scenario the accounted time is accounted for User B, who sent the draft.

Wouldn't it be better, if the accounted time is saved for the user performing the action, as soon as the action is completed?
E.g.:

1. User A creates a drag a records his time units spent.
   On draft save the spent time will be accounted for User A and the field for the accounted time is reset to 0.
2. User B reviews and edits the draft.
   Since the accounted time is 0 again, the user is now able to just add his time spent on the ticket and as soon as he saves the draft again the spent time will be accounted for him and the field for the accounted time is reset to 0.
3. User C finally reviews and sends the draft.
   Since the accounted time is 0 again, the user is now able to just add his time spent on the ticket.

If this would be possible the ticket would still have all recorded time units accounted and the recorded time would be separated to the right users.

No files or tests are named. Start by locating the draft save, review, and send entry points and tracing where time units are assigned to users. Done means time entered by each user is recorded for that user when their action completes, the field resets, and later users can record their own time without losing prior entries.