most important cause of fur-balls is over-grooming and in Mandi's case I'm sure this is explained by his neuroticism! This quote says it all!
"watch for the times that your cat seems to want to do something and is thwarted: they will often stop and perform a vigorous licking of their fur in mid-activity, this is obviously nothing to do with real grooming but may be an expression of frustration."
I'm afraid this is Mandi all over!
However I liked this explanation best from Catastrophes:
Furballs: A cat's point of view
We've talked a little bit about the psychological dangers of excessive licking, but there are practical considerations as well. Licking and furballs go paw in paw. Like the human phenomenon known as "a hangover," a furball is a warning signal of overindulgence for a cat. And also like our human counterparts, the medicine can be as bad as the sickness. Quite frankly, the cures for both are disgusting. Furball medicine is nasty, but at least it's not a raw egg floating in tomato juice in your bowl. The truth is that furballs bother the Higher Power more than they do us, particularly because they seem to strike mostly in the presence of fine furnishings. If you don't want to call attention to the problem, be smart and hack discreetly. If drawing attention is the real cause of your furballs, then there's work to be done.
Fur belongs on the outside, and I will keep it there by any means.