It depends.

Wide boards, improperly restrained or finished are more likely to cup or
split. Note, that as far as splitting goes, glueups improperly restrained
become wide boards.

Improperly restrained flat-sawn wide boards finished only on one side are
more likely to cup than quartersawn or random-grained glueups. Glueups
finished on one side only will still cup. In damp enough circumstances, so
will plywood.

Don't even start on the reverse the smile versus consistent smile
controversy.

If your boards are seated in dados and the grain runs the same direction as
the sides they're seated in, it probably doesn't make a bit of difference.
Cut the wood to maximize usage and finish both sides equally.

"heyscott" wrote in message
om...
I am making some bookshelves, and have 1" red oak planks in varying
widths from 6" on up to about 11". To make my shelves at 11 1/16"
thick, I have been ripping my planks down to a maximum width of about
3.5", and joining 4 pieces together.

I had heard that to avoid splitting or cracking of wood, it was best
to rip down to this width and then join back up.

My question is whether this is good advice. Do I really need to rip
all my wood down like this, or can I join two 6" pieces if I want to?

Scott