Although the technique is written on the FCOM, there are too many variables involved to reduce it to a simple thing.
In my opinion, starting flare at 50 ft is premature unless you have too much V/S, in which case is advisable to pre-flare.
Some people starts pulling the yoke up and down like shaking something. I make a progressive pull until I am happy, and I release it a little bit if I have pulled too much or increase the angle if I pulled too little. The moment I retard the levers depends on how it is going. If I have too much energy (speed well above VLS) then I retard early. If I have too little, I wait till 20 or 10 feet. I never do like many I have seen, to keep thusts levers in the CLB notch till touchdown and making a very shallow flight into the runway. It's annoying to hear so many retards and always makes me wonder if the guy is incapacitated or something.
I consider a perfect flare and landing when I touch down with very little "floating" but softly and with not too high a pitch attitude. When I do it like that (not as often as I would like) I notice clearly that the landing roll will be very short and I will need to make little use of the brakes, even when I am heavy.
It really depends a lot on your V/S, the margin to VLS, the weight, the flight path angle...