Previously in Guo Fu -vs- Miao Renfeng, it was identified that a half-injured Miao Renfeng could keep opponents at bay outside the distance of 8 feet. I interpret this to mean that his palm wind was effective to a distance of 8+ feet. At first, this may seem very impressive, even stacking up to the standards of Song era martial arts. However, is that the case?
In DGSD, there was such a passage:
鸠摩智掌声呼呼,群僧均觉这掌力刮面如刀,寒意侵体,便似到了高山绝顶,狂风四面吹袭。少林寺辈份较低的僧 侣渐渐抵受不住,一个个缩身向后,贴墙而立。玄字辈高僧自不怕掌力侵袭,但也各运内力抗拒。
Jiumozhi's palm wind felt like fiery cold wind blowing in your face. The low level Shaolin monks could not take it, so they began to step back. However, the Xuan-generation monks could withstand the palm wind by generating internal energy.
In this example, we can see that the more power you have, the more resistant you will be to palm winds.
Another example from HSDS:
张无忌和玄冥二老此时各运神功,数丈方圆之内劲风如刀,那三名好手怎能插得下手去?
No one could come within several zhangs to Zhang Wuji and Xuanming Elders because their palm wind felt like fiery blades scratching your face.
But suffice it is to say that a high level fighter would have no problem coming close to them.
Anyway, what I'm trying to say is 2 things:
1) Miao Renfeng's opponents in FOX could not come within 8 feet of his palm wind, but that's because they are weak and cannot withstand palm winds.
2) It is nevertheless VERY imperssive for Miao Renfeng to do a 8 feet LDS. However, it makes me wonder whether weak fighters in Song era can do it or not. We have seen some subpar fighters such as Deng Baichuan and GREAT YIN YANG PALM Yue Hou demonstrate LDA-type feats. I wonder if people weaker than that, such as Zuo Zimu, could actually do a 8 feet LDS. It's possible that even if they can do it, the wind would be too weak to have an effect on anybody.