You can do what you like. Most of the 6 or 8 I own have carvings on only one side since that's all that shows and the flat inner side does lie flater that way. But I do have one with carving all round, so it's really up to you.

I'd go to really good carving on the outter side myself, but I'm talking through my hat since my only experience in knife making was rounding off and polishing a block for a dirk I never finished. (My exwife feel heir to it when she divorce me!)