to shred as quickly as possible, is it better to plant all your fingers on a string to play the pattern for that string or put each finger down at a time when it is needed.

for example,
to play


on a given string, would i put down each note only when it was to be played or have all four fingers down and pull off fingers to get the correct note? I hope I explained this well.
Plant them, you will need less effort to fret and it will sound smoother. (Less movement = Better Technique).