My understanding is that the EFE drill is a Top Speed session… With proper form (which is always the aim), and no forced effort whatsoever (Charlie’s quote on one ‘efforted’ run was “I don’t want to see that kind of power” ) top speed should be gradually achieved. (top speed is usually not perceived by the person running, but by the observer. It is my understanding that a very experienced sprinter recognizes top speed when fully relaxed )
Depending on your level, you should start with a 10m accel and hold for 20m. Then, the aim should be to gradually increase the acceleration length, and not necessarily the top speed F(ast) increment of 20m.
This should lead to a ~40m acceleration + 20m top speed for a 60m run.
(I don’t agree that the EFE drill is a sub-max drill)