Is designating knives to avoid cross-contamination necessary? I have a friend who assigns one knife for cutting raw meat, another knife for cutting fruits and vegetables, another for cutting cooked meat, etc. Is washing one knife after each specific use not sufficient to avoid cross-contamination? (Note: different cutting boards are assigned for different food types as well)
Using separate cutting boards is advisable, but separate knives are unnecessary. 90% of my cutting is done with my chef's knife. I don't own two of these, nor would I use a subpar knife for the job.

I almost always find it most convenient to start my preparation by cutting the veggies, fruit, etc. first and then finally cutting the meat last. Then you can wash your knife once and be done with it.