I've been watching tuts like mad all day lol...took me 4 hours to finish it. Hopefully it won't take as long next time
If you get into more difficult pieces it might take longer, but it is definitely a good thing that you are practicing and learning.
skip sai go photoshop no contest also if youre gonna poke at cell shading really poke at it http://imgur.com/gallery/FAW4O its a good guide and reference i use often