And, as it happens, Shampoo has risked her own neck to save Akane lots of
times - She *always* goes with Ranma to rescue her, and in the Phoenix OVA,
she actually catches her, and prevents her from breaking her neck. 

	She always goes with Ranma to rescue Akane so that Shampoo can be 
there to make sure the kidnappers done their job right.  The only reason 
Shampoo followed Ranma to save Akane from Tarou, for example, was so that 
she'll kill Akane.  The Phoenix OVA was just some effort made by the anime 
directors that try to make Shampoo look like she's nice.  Never 
happened in the manga.

Hmm... in the manga Shampoo did catch Akane... but it was only there for the
bimbo to make a slur about Akane's weight. The rest of the time, Shampoo 
does try to kill Akane...

Kun-chan...