“they had special siyata dishmaya that in the few hours remaining”
In the time of Rebbe, such “chassidim harishonim” no longer existed. That is why he called them “harishonim” which means from an earlier era.
Why?
Perhaps by his era there were no longer such spiritually inclined people; or there still were, but the special siyata dishmaya (Heavenly assistance) that allowed them to pray 9 hours a day was withdrawn???
Did such “chassidim harishonim” re-appear in later generations?