Having equal length speaker wires is a bit too snake-oily for me.
Anyways, here's one argument for conduit:
When my house was being built I made quick random guesses at where the speakers and electronics would end up, and had the electrician pull wires and install outlet boxes in all the appropriate locations. That went fine.
Then a different crew was finishing the wood floor (2x6 T&G on beams) and in the process the amplifier ends of the speaker wires all got caught in the floor polisher, whereupon they were variously pulled out of the wall, stretched, snapped or just friction-burned. I could have raised a stink but by then I had already decided that I wanted the electronics in a different location so wouldn't be using the wires anyways.
If I had used conduit I could have probably fished a new string through and pulled replacement wires. Spare wires probably wouldn't have helped although I guess there was a non-zero chance that only one wire per pair would have been done in by the polisher.
On the other hand even conduit wouldn't have helped after I decided to move the electronics, so give electronics positioning some careful thought and remember that an IR extender (which I didn't know existed during the initial design) can make a out-of-the-way locations become usable.
Don't forget to wire for Atmos
