Self-defense on the "ground" is probably the most uncomfortable thing to learn for most women.  There is no "personal space".  It's hard to move.  It's too much like a real sexual assault.  That, of course, is why it's so very important.

Yes - IF you are willing to train in their use and practice regularly.  A woman who had been training in the martial arts for a couple of years started training with me. 

She said her husband had asked her how long she was going to keep training.  He said "how long does it take to learn this?"  Her reply was that personal defense is not like algebra - you don't learn it and you're done.