Hey buddy! As far as the 'generally accepted' part, where are you getting that from? I'll admit I haven't kept a close eye on the research literature but I haven't seen anything about recovery kinetics of pituitary post cycle in there. In fact at least one case study reports the opposite, and anecdotally we all see the same posts ("Help! I cycled and now feel like shit 6 months later") in fairly moderate frequency.
I should clarify my remarks first--my position is that using hcg for the last 2-4 weeks or so of higher-than-natural testosterone is enough . This is also why I would rather use 750 iu/week than 500 iu during the whole thing. This is pretty well in line with what Bill Roberts has suggested in the past as well, as he has mentioned either using it on cycle at ~500 or in the last ~4 weeks at 750-1500 per week. Because the OP is already using 500 iu and his values are still flat-lined (which shouldn't be too surprising for obvious reasons--AAS use as well as hcg being an LH analogue) I don't see any reason increasing it now while still on the cycle will help. Keep in mind I am not suggesting he go OFF hcg.
Also, typically long term hormone administration has certain feedbacks that come into play with it--the HPTA with steroids, etc. With very short cycles like 2 weeks you see almost no real disturbance, but the longer the cycle the longer the disturbance if no steps are taken to mitigate those feedbacks the harder and longer recovery is. This is the whole reason PCT is necessary right? And it happens in numerous other areas besides AAS use. Well, if one's goal is to restore natural production I don't like the idea of exposing the body to supraphysiological levels of an LH analogue for long periods of time. Now I will grant that the body's sensitivity to hcg dosing doesn't seem to be overly 'finicky' for boosting testosterone, but I don't really see a huge benefit to long term hcg use during cycle as long as you get ~4 weeks in at the end and clear ahead of time for SERM use.
Since he's using 500 mg of test E the approximate point of reaching natural concentrations will be about ~3/4 weeks after his last pin (500 > 250 > 125 >62.5), following which he would start SERMs. That leaves 1 week at 500, and 3 weeks at 750+. Half life of hcg is ~ 1 day so only a few days are needed to clear. So if for some reason my suggestion to increase at 1 week post pin is disagreed with it's not really all that problematic for me and he can start a week or two earlier.