the N also has 40 degrees available, and they work very well, too !
Oh dear - I must try and learn to stop answering from memory - it obviously isn't what it used to be (to be fair its at least a year since I flew an 172N).
I've had a look in my check lists, for the short field speeds and found the following (with the caveat that for maximum performance you should refer to the POH for the specific aircraft)
172 models L, M, N, and P
Short field approach, full flap 61KIAS
Normal approach, 20 flap 55 - 65 KIAS*
172 Model R
Short field approach, full flap (30) 62KIAS
Normal approach, full flap 60 - 70 KIAS
172 Model S
Short field approach, full flap (30) 61KIAS
Normal approach, full flap 60 - 70 KIAS
*No, I don't have an explanation as to why the speed range for a normal approach is below the short field approach speed.
Brooklands