How often to demagnetize mc cartridges?

Depends on one's amount of playback. For me, it's every 6 months.

Demagnetise MCs?!? 🤔 
Ah... never! Ever. 😱 😲
M. 😌

I never do that, only Cardas Frequency Sweep LP for MM and MC

Never.

All the best.

JD

Dear @wcheng2 : I still have the same Sumiko you own. I used several years ago and in those old times I thought it makes that the cartridge recovery its " transparency " or something like that.
I used till the fluxbusting damaged one of my cartridges, I can't remember which one, burn-in one of the coil wire and I always followed the Sumiko precise instructions.

In those times I did too with MM taking the cantilever/stylus out.

So it's hard to say if it's safe to do it with LOMC cartridges and if with today designs really makes a recovery " up-date " in the cartridge performance. Maybe I will test it with some of my LOMC cartridges. We will see.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.