I didn't say 'throttle off steep glide approach' (though there are occasionas when that's appropriate). I said an approach steeper than 3 degrees. 3 degrees is ludicrously shallow for a draggy, slow, light single. It's like taxying with the brakes on - loads of power against the drag!
One should think what is appropriate. 3 degrees is not normally appropriate for a 172 unless it is using the ILS or, as I said, going for a high-power against drag short field landing.