Recessed lights vary in intensity and size. the higher your ceiling the more floor space alight will illuminate.
 
  in general ,recessed light should be 4 feet from each other.

  most rooms are not sized to accomodate this, so you will have to adjust your calculations. once you start installing recessed lights  you will find that many have to be moved.

  several inches from their amin location.in order to avid hitting joist  our crew are able to install any recessed lights in any size that you  want to have .