If you're going to use low reps and achieve the benefits of doing so (less fatigue vs high reps), the quality of your technique should remain high and top priority over everything else for the entirety of the set. Otherwise, you're just causing unnecessary fatigue to synergistic musculature if you’re “cheating your reps” to a degree, and consequently, leading to lower levels of motor unit recruitment for the agonist (target) musculature. More fatigue and a worse growth stimulus just to use low reps is not "optimal.." Make sure your technique is top notch; make it a priority first. I see more & more "science-based lifters" literally turning themselves into powerlifters... Lastly, keep your tempo consistent throughout the entire set and every time you perform the exercise. This allows you to accurately track progressive overload over time and ensure that you’re truly progressing (i.e., building muscle), rather than just using poorer technique to lift more weight—resulting in misleading numbers (a.k.a. “fake progress”).