I was taught 70kts as a 'bit of insurance' in case I got too slow on final
It wasn't (intentionally, at least) the slab-wing technique, all the PA28s at the school i learned at had the newer wing. With hindsight I shouldn't be allowed out by myself if I couldn't hold speed on final, but back then who was I to argue? Stall warner just chirping as the mains touch... never!
I came back to the PA28 after switching to Robins (the 2160) and being taught to land at the speed in the POH. Before then i'd always landed the PA28 at the speed I was taught, but when I came back to them I had the confidence to land them by the book. It's so much easier at the right speed (which, of course, is
why it's the right speed). The aeroplane goes right where you ask it to go, when you ask it to go there - without that uncertainty of floating on and on a few inches or feet above the runway. It really does become so much easier.