It is always best to try to avoid seams on your deck surface.  Butt joints tend to separate and warp as the decking material weathers.  Depending on the size and shape of your deck design this may be easy to accomplish without any effort or you may have to make some adjustments.  Applying decking diagonally can often reduce or eliminate the number of butt joists on decks that are over 20’ wide.  In some cases you may decide that it easier to use a division board to create one continuous seam across the deck surface.  This technique is used to control the seam and make it appear to be a part of the design rather than a careless afterthought such as random butt joints spread throughout the deck.  Be aware of the limitations of the materials you are working with and give some thought as to what will be the best solution to the situation you are in.