Drag increases with the square of the airspeed (not exponentially).

So increasing airspeed from 55 to 70 increases drag by 62%.

Judgement is needed in round out.

Our Grob 103 can get frisky close to the ground with extra speed, single panel spoilers and one pilot. Older two seat trainers tend to have lots of wing area and small spoilers; so, you can go a long way in ground effect.

But no problem when your aim point is the threshold - much more interesting on hangar landings.

Kinetic energy remains constant with constant airspeed. On final we are using drag to dissipate potential energy instead of allowing it to convert to kinetic energy.