I have to agree with Voldmer. Why is everyone saying the picture is inaccurate? Every website you may find with tutorials basically say the same thing:

Lay in your bed
Don't move a muscle
Ignore all distractions (itches, etc)

That's exactly what the picture says. Just because it doesn't include things like 'do it only in WBTB', doesn't mean it's inaccurate. The picture looks perfectly accurate to me, just incomplete.

There's a difference between inaccuracy and being incomplete.