Desensitizing versus shutting a horse down

Many trainers talk about desensitizing horses. I think that there is a delicate balance between desensitizing and shutting a horse down. I have worked with horses that are so desensitized that they know longer respond to any signal that is not "Loud". I think that in some cases horses should be left in there natural state of responsiveness. As always, I like to take each horse in a case by case basis.
Let's take a horse that has a medium amount of energy and a basically balanced temperament. This horse may just need exposure to people, places and things. But not a lot of flapping of tarps and ropes etc. Another horse may be very sensitive and reactive. This horse I'd focus on calmer more relaxed slower responses, but not necessarily flapping ropes and tarps. I may do a little desensitizing with a very fearful horse. But only after I'd done a LOT of Liberty work at which time the horse probably would only need a little desensitizing after we had trust and connection. There is a question to of breaking trust which has been built by over desensitizing. So the question is do we need to do much desensitizing if we have a good relationship working and or playing with our horse? Mostly our horses need our leadership, patience, and calmness to get them through new experiences. They need to be allowed to explore an object at liberty or given the space on line to approach in their own time when curiosity replaces fear which it usually does in time. Time is another question. A lot of horses just need time to get comfortable with things in their environment. I want a horse to stay in their naturally balanced state of awareness unless they are what I deem to be in an unbalanced state. In some cases flower essences may be appropriate for these horses as opposed to desensitizing. Food for thought...