The note distance is the distance between two notes and must be related to the note duration for optimally readable sheet music.
An eighth note should generally take up less space than a quarter note. Usually you will want a compromise between fully proportional (space occupied is directly proportional to note duration) and equidistant (all notes occupy the same amount of space).
MusiCAD uses the shortest resp. longest duration occurring in the score as the basis for the minimum and maximum note distances to display, with the shortest note given the shortest note distance. Note spacing is specified under note layout dialog. With the keyboard shortcuts <ctrl-> <ctrl-> you can easily adjust the note distances through the associated layout templates.
A smallest note spacing of 100% corresponds to leaving two notes at least half a unit apart. If the smallest note distance is set to 0%, the shortest notes will just touch each other.
Largest note distance 100% corresponds to 2 times the smallest distance. So 50% equates to equidistant. Depending on the minimum and maximum note duration in the score, 200% to 400% will almost amount to proportional. In practice, a largest note spacing around 100% will give an optimal note pattern.
Minimum note spacing 100%, maximum note spacing 100%; the longest notes take up twice as much space as short ones. This is the 'default setting' and contributes to a pleasantly readable score.
Minimum note spacing 100%, maximum note spacing 50%; all notes take up the same amount of space. The distance between barlines is therefore almost exclusively dependent on the number of notes (equidistant).
Minimum note spacing 100%, maximum note spacing 200%; the longest notes take up 4x as much space as the short ones. Because the longest duration in this case is 4 times the shortest duration, each note takes up proportional space. Stripes are therefore always about the same distance apart.
Minimum note spacing 50%, maximum note spacing 100%; the longest notes again take up 4x as much space as the short ones, with the shortest notes touching each other. Also in this case the layout is purely proportional, only the notes are now closer together (the shortest notes just touch).
After the notes have been spaced on the staves in this way, on each line the remainder of whitespace that remains after the last full measure has been found is distributed over the measures that do fit on the line, provided that the last measure is more than the line justification percentage is filled. The final distance between the notes will therefore usually be greater than might be expected on the basis of the set note distances.