For the sake of your fellow designer, please organize, color code, and label your layers before handing the PSD off.
The position of the layer should be relative to where it is on the page. A header group should be near the top and a footer group near the bottom.
Unused or hidden layers should be deleted if unnecessary. Deleting 15mb to 20mb of dead weight is crazy.
It's no fun wasting almost an hour trying to clean up someone else's layer disasters.