@Ticker mono length behind the ball varies by personal choice and from the reports here, any length catches fish.
I believe it's speed, turns, popping the release, current that changes the lure's action.
Personally I've had 50 foot leaders, 25 foot leaders, and shorter on lead core, and all caught fish. Haven't tested this year yet. LOL
I was told, start longer than you need/want, shorten as required, and replace when necessary.
Far from an expert, I enjoy myself on the water, (for the most part LOL) and certainly don't have an exact science on my leaders.
Even my dipsy leaders vary in length, if one is longer than the rod I have an extendable handle net and the guy with the net is always in front of the person with the rod. Never an issue.