and whats the reason for NOT having full flap on a C152 at 500 ft?
full flap, plus a very steep approach into a tight field? then you can do a glide approach with full flap in any aircraft.
Because you have a couple of barn doors hanging out the back creating heaps of drag. This in turn requires you to use lots of power to maintain the profile. I've done my fair share of short field ALA operations and a standard approach profile IMO is the best way to get the job done.
Sometimes in the 172s/152s I'd leave 20 degrees out and land with that! Lets face it, they will land flapless in less than 400 meters!