Pros are going for absolute maximum gains so hey use 3g's of gear + 10IU of Gh + insulin. Gaining every last ounce of muscle with little regard to long term health is their MO. You think You're gonna get 6x the gains by going from 500mg of test to 3,000mg? Hell no.
If you're an average joe trying to look good and get a little jacked, like most steroid users I don't think going over 750mg a week of injectibles is a very good idea. And I'd rather see 250 test 250 deca 250 EQ than 750 test. Same gains or better with much less chance of sides like hair loss, gyno, or prostate issues.
If its an ego thing and you're trying to be the baddest dude in the gym, go hard with it but just know that you will be shortening your lifespan at a faster rate due to the cardiovascular side effects. Whatever floats your boat though.