The Rebbe's expectation

There can be no room for doubt. Times have not changed. Here the Rebbe makes clear that all Chassidim are expected to davven according to the Kuntres HoAvodah and Kuntres HaTefillah of the Rebbe Rashab, for an hour or at the very least, half an hour:

With respect to Avodas HaTefillah (the service of prayer, i.e. lengthy prayer according to the Chabad tradition), the Alter Rebbe brings in his Shulchan Aruch as a matter of practical Jewish law that “One who prays should wait in the place that he prays for an hour before Tefillah in order to focus his heart on Hashem ... and one hour after Tefillah ... and the original pious ones would wait for a full hour of the average hours, of which there are 24 in a day.” (Orach Chayim 93:1) He adds, “So would the pious ones and the men of action do: they would seclude themselves and concentrate on their prayers until they reached a state of divestment from physicality.” (ibid. 98:1)

Tefillah should at least conform what is explained in Kuntres HoAvodah and Kuntres HaTefillah. Especially since over time tens of discourses of the Leader of the Generation [in this context, a reference to the Previous Rebbe] have been released concerning Avodas HaTefillah. Let everyone make a reckoning for himself: When was the last time that he davvened with the preface of Hisbonenus?

I don’t wish to point at a particular person and ask him this question, in order not to embarrass him. However, every person knows within himself, and he should think [about this] to himself, when standing in front of the mirror (as is the custom of the country, that before leaving the house one gazes at the mirror to make sure that his tie is straight, because one must be careful to respect people [kovod haberiyos]) and decide that this message is directed to him: When was the last time that he davvened with the preface of Hisbonenus for an hour, sixty minutes or even half an hour, at the very least!

It can be added that this calculation can be made not only concerning Tefillah during the weekdays, but even concerning Tefillah of the day of Shabbos: When was the last Shabbos that he davvened with the preface of Hisbonenus?!

Hisva’aduyos 5748, Vol. 3, pp. 214-215.