Why exactly is it insanity? I like the 3 strikes better (my only concern is drug crime and other non-crime) - 3 separate occasions of disregarding others' most basic rights establish a clear pattern; the society reciprocates by not respecting the rights of the criminal as it protects itself from them. It's only incidentally a punishment, it's really removal - in fact, humanistic removal, the more cost-effective one would be execution.

Now, in case as unique and clear-cut as that of Breivik, I would advocate for an extremely rare application of actual punishment-punishment - e.g., keeping him alive for as long as possible while torturing him.

As for three-strikes-society-removes-you, that's probably my favorite part of the justice system in the US.