At my old job we had lockers and part of my job was to make sure they were empty for the next occupant. A lot of people would leave their locks on the lockers and I'd have to cut them off. We had a pair of medium sized bolt cutters to do the job. I'm not a big woman but I'm strong for my size. I was always surprised at how easily those bolt cutters sliced through the hardened steel locks, like buttah. Even my weakling boss was able to use them in emergency situations. So I'm sure that they slice through most cables like there is nothing there.
That being said, I've got 3 cable locks, 2 medium priced with the lock integrated and one I use a master lock with. One goes through the front tire frame and whatever I'm locking to, the other the rear tire frame and whatever I'm locking to and finally the last one is to attach the frame to my helmet and whatever I'm locking to. If I want to go lighter, I taker just the heavier of the cables and a couple of keyed pad locks. I lock the front tire to whatever is available and put a padlock on each tire hanging out so that it will hit the frame when the wheel is turned. Mostly I know that all I'm doing is making my bike a pain in the butt for someone to try and steal, it's just a deterrent and if someone wants it, it'll be gone. But if it's a choice between my 1991 trek with motor or someone's swank new beach cruiser, which one is the thief going to go for? I always assume it'll be the easier sell. And around here, the easier sell isn't going to be the motorized bike.
I've never had a bike stolen even when I lived on campus and people stole bikes all the time and I was riding something worthy of being stolen.
The big thing I worry about is someone stealing the seat, not that it's ever happened to me, but I see a lot of abandoned bikes sans seat. A thing I read and plan on trying is to take a length of bike chain, slide it into an inner tube, thread the chain and tube through the frame and then the seat rails, then connect the bike chain to itself, cover the whole thing with the innertube and then ziptie the tube in place, put seat up to where you normally ride, keeping the rubber coated chain tight. Supposedly the rubber and the bike chain don't play well with bolt cutters.