Hi,
I've asked myself much the same questions in the past and come up with no hard and fast answer. I'm still torn between two thoughts and as a result I change my mind with the weather! LOL
For a while I was convinced by the "3 weeks on, 1 week off" argument, but I took it a stage further and tapered down to the 'off' point and then started again on full dose for a few days before slowly dropping. However, then I read a good paper, by a doctor, which as a side issue to the main topic pointed out that in girls going through puberty much of the breast development takes place before periods start and up to that point there is no significant hormone fluctuation, although the quantity produced does increase. Once periods start then so does progesterone production and the whole complicated cyclical level thing ( which varies from hormone to hormone at different times of the month).
So at the moment, I take my standard 2000mg PM per day ( plus SP) every day, but at roughly monthly intervals I halve it for a day or two. I can't be sure but when I go back on the full dose I feel as though there is some increased activity.
On the subject of GABA etc. I started off with GABA and PABA daily.
I dropped the PABA when my first lot ran out and didn't notice any difference. I continued with the GABA for at least 6months, but for a totally unconnected reason, I had a couple of weeks break after about 3 months and I also stopped taking it a couple of weeks ago. However last night I did actually take it again and when I looked in the mirror as I got up, I was half convinced that something has happened in the night, growth-wise. Now, I've also just realised that the break I had at 3 months, which coincided with a break in PM and SP ( all due to a holiday) was when my 'growing pains' started - whilst laying on a sunbed by a hotel pool!)
I had never previously seen anything suggesting that GABA is also naturally produced cyclically, but then this morning I get up and read your post, after thinking that the break had done something! So perhaps there is something in this theory. I think in the light of this, I'm going to consider monthly PM reductions and a GABA break every 3 months.