An all-female recruitment cycle could also be called a no-male recruitment cycle, but I suppose that wouldn't sound good.

Direction from the top of the company followed by accountability from everyone will probably move toward any desired outcome, but I contend that the main issue is that most companies secretly don't believe that "percentage of female engineers" is a goal worth pursuing to the exclusion of hiring as much top talent as possible.

My guess on this experiment is that the company didn't hire as much talent as they could have otherwise because of such strict quota measures, and that this isn't something most companies are going to jump to do. Most companies just want to succeed.