Mine can get REALLY BAD! So bad they get infected and they bleed and I can't stand.
BUT, and this is GOOD news, I purchased a Homedics Electric manicure/pedicure kit. It has 7 attachements which DAWNED on me, most are Sanding tools. I have been sanding my heels now for about 2 weeks. I knew I couldn't make much of a difference all at once so I go at it once a day then apply a thick moisturizer after then put on socks and shoes.
I used to razor them a little at a time but couldn't really make a difference with the dry and hard surface on the sides of my heels. The Sander is Amazing. I wish I had thought of doing this a long time ago. It feels So different to be able to actually FEEL my heels now instead of that hard, I mean ROCK hard layer with deep cracks.
I will take a pic of this kit so you can see what it looks like and the attachment I use on my heels. It's the BEST thing I have ever done for this problem which I have had ALL my life, even as a kid.