Michael Merzenich, Ph.D. is a pioneer in brain plasticity research and the author of more than 150 peer-reviewed articles. He has received numerous awards and prizes, has nearly 100 patents and has been featured in hundreds of books covering topics such as learning, rehabilitation and plasticity.
There shall not be more than the equivilent of four quarter bends (360 degrees total) between pull points, for example, conduit bodies and boxes. ansi/tia/eia-569-b: 8.8.2.2 Bends
For the strongest concrete mix, you'll want to premix the concrete with the proper about of water, before you pour it in the hole. The lazy way is the way he wants to do it and you will not get the strongest mix. Also 1-1/2 bags per hole is about right for a 4x4 fence post. Also remember, the depth of the post hole should be one-half of the above-ground post height. (Example: For a 6' above ground post, use a post with an overall height of 9 feet and place 3 feet in the ground).