Conduit is always overkill. Bear in mind that a 1/2" conduit permits nine THHN wires to be pulled in and that is assuming that it is a full run with up to four quarter-bends (360 degrees). Of course, solid copper can endure much higher pulling tension than voice/data cables, or so they say.

10-12 foot runs, which I assume are stubs from outlets into the ceiling area will have minimal impact on the cables. Runs this short can practically be dropped down the conduit with minimal hand pressure. With that being said, I can't imagine why 3/4" wouldn't be more than enough for a typical outlet location.

There are two reasons why I would not worry about sticking with 3/4". Number one is that there is plenty of room for at least six CAT6 cables in it. Number two is that who is even going to be around forty years from now to question your judgment? 3/4" is the industry norm today and you should just stick with what is tried and true for at least the past twenty years.

Ed Vaughn, MBSWWYPBX