Thrust angles are a good thing to watch for. Reason I say this is my friend built a scale model of his Cessna 140, To scale. That was his mistake, he didn't offset the engine and cowl, or the rudder angle to overcome the P-factor. His maiden flight ended rather quickly as the plane flew left on takeoff. It flew very nicely straight and level, but to the left. It went behind a tree, and he chopped throttle after he lost sight of it. Had he kept throttle on it would have circled the tree, flew over the roof of his barn, and he might have been able to recover it. He doesn't fly much rudder and that I think doomed this flight, he might have been able to straighten it out, since ailerons weren't doing jack other than keeping the wings level.
His mistake was not providing enough offset for the engine thrust, so seeing it first hand, really makes an impression....so did his plane, in the ground.
I have a new 4*120 with DLE20 on it, and noticed that I need to add a couple washers to the left mount to correct the left veer when the tail wheel comes up, I had forgotten about that from the first one when I built this one. It just needs a slight correction to the right. Maybe when you do taxi tests with it, getting the nose wheel off with mains on the ground will give you an idea if you need to add thrust angles. I dont fly Trikes, so dont know how else you can find out if you need to adjust the thrust.
That does make me wonder though, on a multi engine plane that doesn't have the prop in front of the rudder, how does P-Factor affect it? If all four engines are 0* thrust, and properly synched, would it even be a factor? My only experience with twins is my Twin Otter and it came as an ARF. Would thrust angles be added in the event of engine failure?