Oh it surely does work, but it's better if you don't do it alone.
Many ppl go way too fast in this. If you are really triggered, then you need to begin just thinking about the situation and how safe you are thinking about it...
You can always do flooding, which is a close encounter rapidly, but you really need someone who knows what they're doing to walk you through that (if you're ready at all for it) because you can be retraumatized.
The desentization comes as a result of your becoming used to each step of the process... thinking, talking about it maybe, visualizing, viewing actual from a distance, touching, etc whatever the triggering aspect is... you stay at each level until you don't feel unbearable fear etc. Then move on to the next level (closer, more vivid etc.) That IS the work.
Feeling safe is key, good self talk, rational talk, creating a new perspective... while experiencing the uneasy feelings.