Doing the math: increase and decrease evenly row over row

I've recently received a few questions about a technique used in many of my patterns:
"SC across, INCR 3sts evenly over each of the next rows, trying not to place increases in the same place row over row."
Firstly, the instructions are written this way to allow flexibility and ease of creation. Once you understand it, it's easier to complete using the "technique" versus tracking each row on a pattern sheet(especially if you happen to be travelling). And if you are creating more than one, it allows you to find the formula that you like the best (although I know I do it differently every time!)

OK, now for the math! The formula works thusly...

random number(Stitch count of row/Number of Inc)

Explanation:
OK, say you have 24 stitches in the row, and you need to increase 3.

1. 24/3=8


2. now choose a random number from 1 to 8, let's pick 5... meaning we'll increase in the 5th stitch of our repeat


3. so we'll work the row like this: SC next 4 sts, inc1 in next st (the 5th st), SC next 3


4. repeat 2 more times to complete the row, for a total of 27 sts.


5. do this as many times as the pattern calls, just choose a different random number every time (at least 2 higher or lower than the previous row).

Now how about decreases? Same thing...
OK, say you have 24 stitches in the row, and you need to decrease 3.

1. 24/3=8


2. now choose a random number from 1 to 8, let's pick 5... meaning we'll start our decrease on the 5th stitch


3. so we'll work the row like this: SC next 4 sts, dec1 in next 2 sts, SC next 2


4. repeat 2 more times to complete the row, for a total of 21 sts.


5. do this as many times as the pattern calls, just choose a different random number every time (at least 2 higher or lower than the previous row).

I hope this helps make the pattern instructions clearer ;D