I.M.H.O. It all depends on who is making the PSD no matter if it’s low, medium, or high complexity. When you get the PSD from someone with a web design background and knowledge, then this person, probably, will take into account important web design factors such as CSS margin, padding, font-size, floats etc, which makes the job a bit easier. When on the other hand the design is coming from someone with no web design background, the job will take you way longer because they just deliver what they think looks nice without any consideration if it is even possible.