Timing can be everything when developing raw land. Changing demographics, a shaky economy or other uncontrollable factors must be weighed. Building a new apartment complex when there is a housing surplus doesn't make sense. Nor does spending money to develop your parcel when already-developed land is easily available at a lower price.
If you already own the land, it might be best to wait until there are changes in the market or the economy picks up before developing. If you haven't yet made your raw land purchase, be willing to walk away if the time isn't right. Don't get so attached to your land parcel that you make the wrong move. There will be other days -- and other parcels -- available.