I deliberately crossed controls to lose that extra bit of altitude, which worked for me, but the instructor (for whom I had the greatest respect) commented that slips didn't really work for high-wing aircraft.
and...
Sideslips are not permitted with Flaps extended is my recollection on most GA types?
Slips in the C172 are not recommended at maximum flap setting, due to oscillation in pitch associated with disturbed air flowing over the tailplane. Being unredeemably contrary by nature, I tried it once. The oscillations were noticeable at 30* flap and negligible at lesser flap settings as per Cessna's recommendation.
Other light aircraft slip very nicely, in my experience!