On a PFL to a field, your aim point should be 1/2 to 1/3 into the field. Once you have that absolutely made in a C-172 adding flap past 20 degrees brings you in steeper and gives you more field to land in.
My last C-172 checkout included a number of surprise simulated engine failures from downwind to a short runway. I like to do it short and steep and would end up at 40 flap and pointing the thing at the end of the runway.
The roundout of course has to be done not too low and not too high -- and you do need to carry enough airspeed to have enough elevator control to raise the nose when you need to.