How often to demagnetize mc cartridges?

I don’t seriously disagree with those who say never to use a flux buster like the Sumiko. As I mentioned, I only and occasionally use the Cardas test LP for that purpose, and it does seem to rejuvenate MC cartridges. My rationale is that I am fairly sure that playing an LP is not going to damage the magnet in the cartridge. It is probably a very gentle process, if it actually does any good at all. But one cannot say often enough, never demagnetize an MM cartridge. The same probably holds for an MI type, although maybe less dangerous in that case. In fact, I once owned an Aesthetix Janus preamplifier which has a demagnetization circuit that you can switch in. I was so leery of accidentally damaging any of my precious vintage MM cartridges that I disabled that circuit.

Never done it.  No need. 

Did get the manual but it doesn't mention or recommend time between treatments.  

Thanks for your responses everyone!  I think I'll just try using the fluxbuster every few weeks or so.

Is the primary question not about ''coil core''? Iron core is used
in order to increase the output.'' Coreless'' kinds as the expression
suggest have no ''core''. It is this ''iron core'' which get ''magnetic
saturated'' and may need demagnetisation? 

When I responded earlier, it was because of my use of the Cardas lp.