Not necessarily.

I bought a pair of quick slip on/off heels for travel to the US. Imagine my surprise when I realised the metal posts in the heels would set off the WTMDs in Montreal and Toronto on flights within Canada! Rather than go through the hassle of getting wanded, having to remove my shoes, my feet wanded separately, and the CATSA agent being all biatchy, I just take them off every time now.

I'd buy another pair, but most heels have those metal posts and make it a moot point.