I have worked on a few boats with every line the same color, I absolutely hate it. Yes you save a few bucks on a spool versus buying
individual lengths, but don't do it. Black lines are fine, no issue at all with a black line or two, but you need the color coding to help identify which line you are grabbing.
As an example, my jib sheets
are green, when there is a big pile of line together if I need to trim the jib
I just have to clear the solid green line... My spin sheets
are red, so when I need to trim the spin I can grab the red line.
Halyard lines are red flecked and green flecked, I bet you can identify which sail they go to without me telling you.
sheets are blue, what color is the main halyard? I'll give you a hint, it's flecked not solid.
By breaking lines down by color it then becomes trivial to tell someone to release the 'blue flecked line on that clutch
bank. Try doing that if they are all the same color.
At an absolute minimum try buying half spools in different colors, then dedicating one color per sail, jib one color, main one, etc. it's not quite as good, but it's a start.