All the experts in the field of weathering say the same thing, whether they are in the plastic model, model railway or any other area of hobbying, and that is to be guided by photographs of the real thing, not by someone else's model.
You might be trying to copy someone else's weathering effects, which in itself could be a copy from some other model, so the variation from reality can get to the point of it becoming unrealistic. You should always use real colour photographs as reference and try to get as close to them as you can by whatever techniques you prefer to use. Then you should be in with a chance of pitching your own weathering at something close to the real thing.