Image by daniel incandela via Flickr
One of my former teachers advocated forte practicing. She employed this at all times. I’m not a fan of full-time use ~ it wears out my hands!
Practicing with the dynamics you’re going to use is just as important. Your results will feel awfully uncomfortable if this is done at the last minute.
However, playing forte is very helpful in learning chords and/or fingerings. When a piece is new, you will learn it faster if you can hear it, and feel it in the muscles of your hands and fingers.
Forte practice works the machinery ~ your hands. You need it to feel the shapes of intervals and chords in your muscles. Having done that, your muscles will recall the shapes. You’ll find everything faster.
Sometimes when I’ve played a piece for a long time, I become sloppy. Notes don’t sound from time to time, or a fingering will slip. Once in a while, a dense chord will morph into one note less. (Hmmm… wonder why it suddenly seems easier?)
Slo-mo practice will make obvious any sloppiness that may have crept in. And the most effective way to correct the problems is to practice forte. It’s a great way to remind your hands what they need to be doing.
Today, however, is good old New England HHH weather. Any movement causes profuse sweating. So I practiced 2 Bach preludes & fugues and 1 Messiaen prelude slo-mo, listening to harmonic structure (playing block chords) & one line at a time. It was useful ~ a cinch to hear individual lines, for one thing.