Sometimes, there is a teaching given in the Nyingma that the most elaborate visualization practices, such--in our tradition--Vajrakilaya are there for the lowest level practitioner (the lowest of the highest in this paradigm). The lowest level practitioner is defined, in this context, as the most intellectual. I'm not making this s**t up!
This, taking a kind of shamatha approach to an elaborate visualization practice, one studies up on all the deities in the mantra, their symbolism and so forth, then takes care to gradually meditate on each detail of the palace (parapets!), bringing one's mind back onto the object as in any shamatha practice. You can see this in Dilgo Kyentse's book on generating the deity--the one about Vajrasattva that was taken from teachings he gave to Kagyupas.
Personally, I started out this way based on my background in Kagyu shamatha vipassana meditation. I think I just assumed we did this this way, and also I relied on some wonderful Ka-Nying lamas to help me understand Mahayoga practice.
I was an intellectual, and an angry, judgmental, and political person, and for me, doing that as my first tantric practice after ngondro was pure gold. I made drawings and diagrams of mandala and all the most obscure deities not visible on thankas, studied up on their significance, and so on. It really unwound a lot of stuff for me.
It wasn't until I spend a lot of time--years-- with my lama that I realized that this was not his approach at all! He is named by other lamas as, along with Alak Zenkar Rinpoche, one of the most knowledgeable people in the world of all things Kilaya, but he reminds us that there was no TV or movies in Kongpo when he grew up. For him, reading up on all that stuff and memorizing it was very entertaining.
We have an oral teaching from the 20'th century master Sera Khandro that articulates this.
[in the] the custom of those who belong to the Ancient Translation School (Nyingma; rnying ma) meditation on the deity and sustaining [the recognition of] your own mind’s uncontrived, abiding nature are not different. Why is that? What meditates is the mind; what you meditate upon, the deity, is also the mind’s natural glow. Moreover, to settle directly in recognition of the mind’s natural repose, without meditating on the deity’s shape, is the deity’s wisdom aspect, the essence of the true body of ultimate enlightenment (chöku; chos sku).
Yes, Greg, she goes on to articulate the way of practicing in the language of Mahamudra as well.
Some, such as Orgyen Chowang Rinpoche, argue that the lamas should not bother with teaching the elaborate practices anymore, such as Kalachakra. He and the charming Dr. Nyida had a debate about this at our center about a year ago. Orgyen Chowang (AKA Khenpo Orgyen Thinley) feels strongly that this is the era for Dzogchen.