This may involve defining acceptable headings, speeds, bank angles, pitch, thrust, SOP and checklist usage. It takes away from the checker the ability to fail a student because they do not do things they way they "like" it, if a student meets the required parameters, they are deemed competent.
But it turns out to be nothing more thana huge box ticking exercise. If you look at the number of seconds from brakes release at the start of the take off run, then the rotation, followed by an engine failure, the identification, the initial climb followed by the acceleration segment until full clean up then setting of max continuous thrust on remaining engine (s) etc.
Now look for example, at the Day VFR syllabus competency based boxes starting with the actual start of the take off roll, you will be able to see a continuous listing of every single "skill" movement by a pilot and these are numerous - each of which must be assessed and ticked.
The instructor or testing officer will need total recall of every facet of the take off and subsequent engine failure procedures in order to accurately assess the student's competency. Most of the time the instructor will not only be unable to write fast enough as the student accelerates from a standing start, he may even miss a box or two while heads down busily scrawling comments.
This is anal marking at it's worst. But yet it is called Competency based marking. Surely it is better for the pilot under test and certainly more efficient, to allow the testing officer to take a broad view of the conduct of the take off and climb out with a failed engine, rather than have to assess so many individual parts and tick the numerous boxes in the limited time available until the next sequence of box ticking for competency begins.