Great question, and the short answer is no. For examples: In 2007, work allocation would continue based on the allocation at the assignment finish date when extending the task duration. In 2010, work allocation would continue based on the Assignment Units. Entering time would simply move the finish date in or out without affecting work allocation. Additional information can also be found in the following technet article: https://blogs.msdn.com/b/project/archive/2010/04/29/assignment-units-in-project-2010.aspx