[Pansy-Mae]

I suppose it could be age related, too. Maybe late starters need more? It's all a bit of a black art with no scientific studies going on - who'd fund them ?

I would expect the opposite considering the decline in testosterone levels as you get older. If there is a correlation between age and needing more pm, perhaps the reason would be the older you get the less efficient the body metabolizes pm?

I tend to agree with Bryony on this point and I think the T level may be not overly relevant in this regard.
I suspect that it is simply that, with age, the body loses the ability to grow/regenerate tissue with any speed. So trying to kick start and then maintain a growth process that is alien to begin with and at a time in life when for GG's the end result is actually diminishing not increasing, means we have to do double or triple or even more.