CS: you are, of course, free to disagree with me regarding the Rebbe. But that doesn’t mean that i’m wrong.
Regarding התבוננות, I base my opinion on my studies of the Baal HaTanya, including Tanya, and his countless Maamarim. Modern-day Lubavitchers have changed greatly both in feel and in practice from the original vision of the Baal HaTanya. I consider myself a Talmid of the Baal HaTanya, not a modern-day Lubavitcher. Whether the changes that have been made to Lubavitch over time are a good thing or a bad thing is not something that I have any interest in debating; it is what it is. But the main point of the original Lubavitch as envisioned by the Baal HaTanya, is clearly התבוננות.
As a side point, the way the Baal HaTanya appears to have envisioned it, you DO IN FACT have mandatory התבוננות every day. It’s called Tefillah. The Baal HaTanya, as you know, wanted every person to daven Shacharis a minimum of 1.5 hours in the morning. When done properly, you can have a proper עלית הנשמה through כוונה בתפילה which is exactly what the Baal HaTanya means by התבוננות.