Probably the basic reason for seeing so many variations in advice is that HCG use doesn't require particularly precise dosing or use protocols. The ranges that are useful are pretty wide.
The main thing is not doing it the wrong way, which is what used to be the norm: allowing the testicles to atrophy for the entire length of the cycle, and then slamming them in PCT.
So long as the testes are in good shape going into PCT, then the HCG use during cycle was fine. This could be from using it in only say the last 4 weeks of the cycle, or could be from using throughout. It could be from using at 500 IU per week throughout, or from using it at 500-1500 IU per week in the last (for example) 4 weeks, though at least 750 IU/week would be better if leaving use towards the end.
It's also possible to use larger doses and get away with it, but it's not necessary to do so.
So a wide variety of advice is given, as often anyone who has done something in a particular way will then advise that way, without necessarily having tried anything else for comparison. Even a doctor, for example, may have always prescribed 3000 IU at a time injections, and never having tried anything less, be insistent that he's been doing it this way for 20 years and his method is proven.