Yerucham — the tomim, chozer, and oived — told us in Homil that he had spoken with the Rebbe regarding zman tefilah (the prescribed time for davening). (Yerucham, himself, davened at length.)
“Ay, there is another motivation there [in davening earlier ], ” the Rebbe told him. “They want to eat earlier. ”
“But when the Rebbe saw from my response, ” Yerucham told us, “that the issue was something else, he said, ‘We see clearly that until davening is completed, the kabbalas ol is still there. ’”
(In other words, the time of preparation before davening should be substantial.)