I have noticed the initial rep feels significantly different for me than the following ones. Maybe some truth to that?
if you deadlift with weightlifting technique as i always did
then the very first part is the hardest, once near the knee its like the easiest thing
because the hardest part is setting up the back insanely tight and pushing off the legs, not pulling on the back, as weightlifters do this exercise
so in my case half deadlifts would be way more effective to hit the spinal erectors i guess
also seems safer because you are well within limits of your flexibility and less chance to snap your shit up if you ask me as long as you dont play the ego game