Why don't you just let people do what they want to f'ing do? Sure, Stacy got great results, but most women are not Stacy and won't get that beautiful firm body from 'just lifting'. Lyle McDonalds explains in plain English that women need more cardio than men to keep BF% down. I lift because I like it, but all women I see in the gym that have a better body than mine are cardio and light weights queens. And, no, heavy lifting for like 4 years did not give me a great bod. I just stalled and kept stalling unlike Stacy who progressed. I have an inkling that most women are like me, not like Stacy. Gods, I spent hours thinking of Stacy and wishing I was Stacy. But Stacy I am NOT.
I am sorry, but it is just so annoying - women by nature are more prone to sticking to the rules. So, they told me to starve, and I tried to eat <1000 cals a day; they told me to run, and I ran 4x a week; they told me to boot camp, so I lifted 10 lbs dbs 120 times for 90 min straight 6x a week. Now they tell me to go under the barbell, so I squat and DL.... and the result are null. Sure, I can do more shit in the gym than before, but I ain't a any better in the looks department.
The efficient thing to do is the one you LIKE doing, to STICK with, and that puts a SMILE on your face when you sweep into the gym. If it's the triceps extensions, so be it. I think just like with food your body will eventually lead you to the movements that it finds the most beneficial.