It's not that impressive when you see the weights I'm doing (see sig), I may feel differently when I'm heaving more significant kilogramage.

The total of the five lifts is only 387.5kg now, my aim is to hit 500kg by November 20. A bit ambitious but what the hell.
You are probably also looking at it through the filter of the 5x5 across, 3x5 work sets is a lower workload. With 3 exercises at 5 work sets each, you're doing 15 heavy work sets a session (leaving aside the bodyweight stuff for the moment). Whereas I'm doing 5 exercises with 3 work sets each... 15 work sets a session. So it's not so different, it's just spread out among more exercises. Which was the point I was trying to make earlier.
It's perhaps slightly harder with 3 work sets for deadlifts than for 1, but I don't believe this is as big an issue as many make out, as I've said before in another thread.
I don't believe much in "genetics" of people like Reg Park. There exists no laboratory test for such genetics, I can't go to the doctor to find out if I have the right or wrong "genetics" for this or that sport or building my body to look a certain way.
So if we succeed we can say it was genetics, if we fail we can say it was genetics, we don't know until afterwards. Thus, "genetics" means nothing in a practical sense. "Genetics" may as well be "prayer" or "orgone rays" or "luck". It's just another way of saying, "I don't know." Well, I
do know how Reg Park did it: through damned hard work, good food and good sleep. And damned hard work!
Before starting on this a couple of weeks ago, I hadn't properly bench pressed for two months, just overhead pressed. I went from 40-80kg, sets of 6, to being able to manage 75kg 3x5, so I didn't lose much benching strength from neglecting it. However, I'd like to get it up higher, which is why I'm doing it. If the routine becomes too heavy for me I'll drop the bench out of it as it's the least important to me - I need to improve back and leg strength much more than chest strength.
The combination of the bench and OHP isn't too vicious, these are only 5-rep sets remember. And my woman is in favour of big shoulders and arms

I think most lifters could do it, but they need a couple of months on three-lift sessions first if they are very unfit to begin with.