depends on low or high res. I suppose I'll comment for low-res (games). Most of my character models take approximately 5-10 hours modeling, 15-20 hours UV layout and textures. My environment models so far, have been comparable (Goblin Tree was about 15 modeling hours, 20 texturing hours). I would suppose experience plays a part too. My very first character took me a month, and it was crap. :p