I think the answer depends on what practice you are referring to.
In neigong and Daoist practices, my teacher never recommended or taught any type of visualization, not even in qigong practice. On the other hand, we did discuss location and characteristics of points and meridians so to say there was no visualization involved is a bit inaccurate, IMO. I believe one reason to minimize visualization is to prevent the conceptual mind from engaging and misguiding the attention and interfering with the practice. My Daoist teacherās core instruction was to focus on the practice instructions and the experience of practice rather than conceptualize, analyze, or follow the intellect. It was more about focusing and training the attention than creating any internal imagery. He even discouraged reading and study in favor of investing that time in practice. While those things have a valuable role in our lives, we rarely experience the world in any other way so it is important to learn to use the attention in a different way so that we are not overly dependent on, and consequently limited by, our intellectual and conceptual faculties.
In Bƶn and Buddhist systems, visualization is useful and widely used.
It is very useful for concentrating, focusing and training the awareness and attention which are otherwise prone to distraction and preoccupation. I think it could be especially valuable to us in this high-tech age when we always have ready access to every answer, image, or explanation we could desire at the touch of a screen. Our powers of focus and attentiveness arenāt getting enough exercise, not to mention our memory and other cognitive functions. In tantric practices, visualization is a core element and itās efficacy can be readily seen in the results of practices like trul khor, tsa lung, tummo, chƶd, dream yoga, deity yoga, and so forth. In these practices, it generally refers to a sequence of steps rather than a single, simple creation of a mental visual image. For example, we may first create and stabilize the visual imagery, then allow this to deepen into a more comprehensive imagination that goes beyond visual representation and may include other senses, then to a more intuitive felt sense of the thing, even a channeling of characteristics and qualities, and finally to simply being, or full embodiment. My teacher would often instruct in a retreat to first visualize, then imagine, then feel, then BE, eventually skipping the early steps when not needed.
Itās important to acknowledge that visualization can mean different things. It can mean creating an internal visual image of something; it can be a wider imaginary representation that can include sound, smell, taste, and feel. It can be more intuitive. It can be to conjure up a memory or a plan. It can be creation of a feeling in the body like heat; it can be to imagine the pain and suffering of others and bringing that into oneās own field of awareness, lots of permutations are possible. I think it is difficult, if not impossible, to entirely exclude visualization in its myriad forms from our practice. For example, even those who emphatically discount the value of visualization in Daoist neigong carry in their minds some representation of the inner architecture, the inner anatomy, the expected and conceptualized characteristics of energetics, the expectations for outcome and so forth. All of this is, to some degree, visualization, IMO, and all of it can be useful.
Visualization is a wonderful tool even in largely physical activities like golf, tennis, music, martial arts, weight lifting, etcā¦ The power of mind is not to be underestimated. I heard a marvelous story of Arthur Rubinstein. He accepted a last minute invitation to play a piano concerto in London, one heād not practiced or played in years. On the transatlantic flight, he spent hours visualizing the score in his mind and playing through it from beginning to end. He arrived in London and performed without error. My music teacher often recommended I use this technique to practice when I didnāt have the opportunity to actually use an instrument.