*Shameless self plug* check out my line of action video Short answer though, it's personal choice/situational. Some artist find it helps to draw the full body along a line of action, some just need it through the torso. I personally like carrying it from the head all the way to the foot.
To be honest with you I don't remember lol. I want to say I probably grabbed them from Pinterest though. Recently I have been buying packs from grafitschool.gumroad.com/ They don't pay me, I just think they are a good artist resource and affordable. Hope that helps!
