I'm surprised. Nowadays when I train a bodypart I pyramid up through moderate rep ranges until I get to a 4-6 rep max. Then maybe drop down to a lighter weight to get more blood in there or to completely exhaust the muscle.
Isn't this how most people train?
I personally don't even differentiate much between very heavy training (3-5 reps) and lighter reps. It's all used together and it's all very much on "training very heavy but making sure by the end my muscles are fatigued and pumped with blood".
I also don't like set paramteres like 8x3 or 5x5 because it tends to put you into a restrictive mindset where you obsess over exactly how many sets you've done instead of how the muscle feels and whether you are adding more weight to the bar consistently.
Instead of all that brainy stuff why don't you just work up through higher rep sets to a few very heavy sets and then drop off a bit and pump out some higher rep stuff if fatigue is an issue? This is not set in stone either like 5x5 or 8x3 and you might find yourself feeling like you want to keep things lighter or go heavier and turn that 4 rep max into an 8 rep one over several months.