Re: Our the longest Night is 971 minutes and shortest night is 442 minutes. This means that 1/7th on longest night is roughly 138 minutes and shortest is 63 minutes so Shaykh (Mufti) Shabbir Ahmed Saheb (HA) is saying that the 1/7th rule cannot be applied to UK throughout all seasons and all intervals.
Yes, which is why I feel that all those hawalajaat mentioning 1/7th to be incorrect actually ought to apply to regular zoning.
See, all that the fiqhi books mention is "Fayuqaddiroo.." i.e calculate.. Now how this calculation is made is Ijtihaad. This is how Allamah Shaami mentions it,
الدر المختار وحاشية ابن عابدين (رد المحتار) (1/ 362)
وحاصله أنا لا نسلم لزوم وجود السبب حقيقة بل يكفي تقديره كما في أيام الدجال. ويحتمل أن المراد بالتقدير المذكور هو ما قاله الشافعية من أنه يكون وقت العشاء في حقهم بقدر ما يغيب فيه الشفق في أقرب البلاد إليهم
If we read Ml. Thanvi's answer about his establishing this principle, he mentioned that the time between maghrib and ishaa is to be time between subh sadiq and sunrise. These are essentially the 2 parts of the 7 parts of the night. In regular zoning they may change.. but in abnormal zone where shafaq ahmer doesnt even set, or subh sadiq doesnt come, these become a precise stipulation of the night into different parts to asses the times of those salah which are mafqud because of the abnormality.
That is exactly what the hadeeth of dajaal pointed towards. Fatawa of many darul uloom simply say for 6 month night and day.. to divide 24 hours into 5 with respective salah differential.. etc. So while in our case the abnormality is not total, we apply this calculation to the abnormal part of the day and for the abnormal times of the year.
That makes good sense to me.

