If you're riding offroad and had boots with heels, they would help keep your feet slipping off the pedals. Keeping your feet on the pedals was probably more important than how efficient it was.

If you now want to ride mostly on the road, efficiency is more important, so get toe clips/clipless and change the set up.

I ride on the pavement - the entrance to one MUT is about 10 feet from an intersection and there is no cutoff opposite it, so I go up onto the pavement. Same thing when I want to use the shortcut into the mall parking lot. I don't ride long distances on them - the up and down of the driveways get really annoying at 30km/hr