The only “competing” that occurs is when one steroid has a stronger binding affinity than another, and mostly relates to specific kinds of receptors. But they all reach receptors. If your receptors all get occupied (if you have several grams of steroids in you), your body will activate more of them to compensate. This could mean more side effects as well as muscle. The number of receptors don’t change, that’s genetic. The number of active receptors do change depending on need. Receptor sensitivity diminishes if your cycles run too high for too long. If you run a test cycle for a year, it’ll be difficult to pct effectively even if you are on TRT because your body will need more now.