It really depends on the picture as to how long it takes to complete.
I am not the fastest drawer out there I must admit and being a perfectionist doesnt help..lol.
I don't think there is one picture I've done that I can actually say I like and that's probably why a lot of my stuff is unfinished, I give up trying to get them right.
I can draw other horses, although I havent done so in a long time. Its just that I havent had the need to really, I only draw for myself and I love arabians so much it seems to be always those that I draw..lol.
I used to own an Appy years ago, his name was Khemosabi, his sire was American I believe. I would of loved to of drawn him but I can't find any photos of him. He was beautiful and he taught me so much. He really was the best horse and he was my friend, I miss him.