First of all it is physically impossible to throw long toss any appreciable distance and keep the ball between 4' and 8'. Let's take 240' and an intial velocity of 80 mph. That's about 117' per second. Over 240' the ball is going to slow down by about 30 mph or 44' per second. That means the average velocity is about 95' per second so the ball is in the air for about 2.5 seconds. In 2.5 seconds assuming a whole lot of backspin, more than most people produce, the ball will accelerating down at about 16ft/second^2. Using .5 * 16 *2.5^2 we get a 50' drop over the 240'. You have to throw the ball upwards a lot and 4' to 8' just won't do it. As a simplification let's say you have to throw the ball up 25' in the air in this case.
Now let's take the 180' postured by some on this site. Starting at 117' per second (80 mph) and assuming the ball slows down about 33' per second we get an average velocity of about 100' per second. That gives us about 1.8 seconds in the air. In this case given our previous assumptions for the effect of backspin and not accounting for the fact that the spin slows down while the ball is in the air the ball drops only about 26' meaning that you have to throw it about 13' in the air. Now the reality is that most people don't get anywhere near that much backspin on the ball, nor do they get pure 12-6 spin, nor is the ball traveling on a straight line so it takes longer to get there than I've calculated. The end result is that you have to throw it even higher than I've noted. This tends to be made up for by the fact that you are releasing the ball from about 4 to 6' off the ground. There's no such thing as long toss "on a line" at 180'.
Yes, the numbers assume throwing with an initial angle upward of about 30 to 35 degrees.