Well, standard flare height is 30 feet but you need to start early in some conditions like high altitude, weight, tail wind etc, or a combination there of.
In our Region of flying, especially Post monsoon, there is a significant difference between direction and magnitude of upper winds which leads to GS mini bringing the aircraft at higher calculated Vapp (or in gusty winds or in case of wind change due diurnal variation). Further as you are going down for flare and landing, matching it with (lower) Vapp leading the N1 demand reducing. This reduction of N1 demand, I believe makes ATHR lazy, has made me hold on to the ATHR for a longer duration waiting to arrest the sink and then chop it to idle. I would say 20% of the times.
I know of people who consistently gives a small check at 50feet or so which wakes the ATHR somehow but results in longer LDAs long flare, in most of the occasions.