It also depends what type of photography you want for your wedding. If you're looking for traditional type shots, you may be able to get away with booking for the cermony and reception. The time between the two could be spend doing the portrait shots. The other, and more popular option these days is "Portrait Journalism". This style basically tells the story of your entire day, from getting ready, right up to cutting the cake and the party. This style is typically mostly candid/natural photos. There are some photographers who will stay the full day with a flat rate for the full time. If you are concerned about capturing your entire day, that is an option that you might want to look into. Full day packages are typically the best deal, and then you don't have to worry about "extra hours" charges. Good luck!