Odds are that it isn't friction within the cable, since they're lined and there's no way you could have worn through the lining that fast.

So the place to look is at the cut ends, and how they line up to the fittings. Often people cutting a housing end up curling the last turn in in the process, so the wire binds on it, so check that both ends are nice and clean with the hole unimpeded.

Then check that the cable run is nice and clean where the cable enters the levers and at the fittings, Any bends at this critical point will cause the wire to rub and bind. Also check that you used the correct ferules to ensure a good fit into the various fittings.

BTW- you didn't say, and I assume you bought kits, but if not, make sure you're not using index housing (the steel runs the long way, rather than like a coil spring). Using index housing in brakes is a serious no no for a variety of reasons.