A wedding table is decorated using several things; the table linens, the china, the centerpieces, place cards and even the silver ware and glasses.
All these things need to fit with each other to give the table a complete look.
Finding that many things that will work together is never easy and decorations don't just have to be elegant and according to the theme, they also have to create a comfortable environment for the guests to talk and eat.
You can't have a two foot tall centerpiece and expect the guests to be able to have a conversation, if the centerpiece is too wide then it's going to take up space for the plates and the table is going to be cramped.
Then there are the kinds of tables you have to decorate; the head table, where the couple sits usually accompanied by close family and the guests' tables.
Usually a bigger sized centerpiece sits at the center of the head table and if it's the long picnic kind, two smaller versions of the centerpiece should be placed on either side of it.
If you were to place a fruit bouquet at the center of the table or any other fresh fruit arrangement then you should place a larger sized arrangement in the middle and two smaller sizes on either side of it to give your wedding arrangements a synced look.
If the head table isn't long or big enough for more than a single centerpiece, then place the smaller ones on the guests' tables.