I will discuss Ovidrel shortly in a new thread elsewhere - see all the info needed there. PCT differs a lot from one individual to the next. It all depends on what AAS's were used, for how long and at what dosages. I have read up quite a bit lately on the subject, but one basic fact is that HCG should generally be used post-cycle. In male hypochonadism(and yeah, if you're on 'roids, that's what you end with!) the general dosage is 2000IU's per day 3 x per week(or atleast twice). This is continued for 3 weeks(in general). Now, here is where things start to differ.... There is a school of thought that provocates the use of single shot injections at dosage time, like in kickstarting your Leydig cells. Then there is the opposing group that feels "pulsing" LH levels with smaller, regular interval injections are better. The outcome of these two methods are still being looked at at which is the better.
When HCG is used, it has two effects - the first is by direct stimulation on the Leydig cells and the second, more potent effect is by increasing the LH level via your main hormonal axis. The LH peak then increases Leydig cell activity and testosterone output results. To me it makes more sense to give regular, more constant peaks in LH than just one, super peak. You see, LH secretion works in Circadian cycles of about 4 hour intervals. This means in peaking LH every 4 hours, will result in more constant testosterone output. Problem is, at what dose. As little as 100mg testosterone injection, can severely suppress your LH, but 100mg Deca again not that much. Then there are other drugs(anabolics) which in turn elevates LH(some orals). So, your cycles nett effect on LH level will determine how much HCG you should use.
Generally, as I use 800mg Test per week, I would take my first HCG at 5000IU's, especially if I come off a course longer that 10 weeks, on the first day. I would split this up in 5 smaller injections every 3-4 hours. My next shot will be 2500IUs 5 days later, then again 5 days later, then 1500IU's 5 later and the last 1500IU's 5 days later as the last shot. Now, this is very close to the medical dose for hypogonadism(2000IU's 2 - 3 x pweek). The other method is to use the HCG every day at 500IU's once, or 1000IU's every other day, but split in 2 x 500IU doses. This is then continued for three weeks. Now, do the maths - it equates close to the same total amount of HCG units per PCT cycle. Another method to use, is to use 500IU's every week or second week while on the AAS cycle - this also improves your initial repair during the PCT and helps prevent a too large suppression on the Leydig cells during the AAS cycle.
Botom line. To me it does not matter which method you use, as long as HCG is ALWAYS part of your PCT.
Obviously, as Conan said, the younger you are, the lower total dose of HCG you probably will need, but again the more Test you use in your cycle, the higher dosage you will need.
So how do you know how much. Play with your balls! Yeah, that's right. Feel them. You will have to experiment with the dose and see when your testicles start filling out again and start hanging "heavier" - then you are probably using enough. Another method is to see what your serum testosterone levels are. Titrate according to this response. As little as 1500IU's HCG per week can increase your test level by as much as 250-300%.
Knowledge is power!