- I tried it and I hate it cause it's too hard, or
- I couldn't understand the directions in the book, or
- I know one cast on (usually the backward loop method, which while it does have its uses, is really not a great cast on for new or nervous knitters, but I digress) and that's all I need.
Another thing that I hear a lot or see in the forums, is that the best way to make sure your long tail cast on is loose and stretchy is to cast on over 2 needles. My own Mom taught me to cast on this way, although I'm not sure she knew why she was doing it, only that it was the way she was taught. In my experience, casting on over 2 needles just causes the stitches in the first row of your work to be bigger that the stitches on the next row. While it may be easier to work that first row, it will generally end up being a bit sloppy, and not stretchy.
The secret to a stretchy long tail cast on, is to leave a space between your stitches when you cast them on. I use the tip of my index finger on my right hand to measure the space so that the stitches end up as even as possible. Tip number 2 is to make sure that the newly cast on stitch isn't strangling the needle, it should be able to slide on the needle easily. Think of it as a hug, not a death grip.
I hope the video helps illustrate these points. I love learning and using different cast ons, but the long tail cast on more times than not is my go-to standard.