Oh boy! I turned up late for the party!
Skim read the posts - few points.
My proposal re. cycles of Bias between disciplines was more to do proportions of training and phases (i.e. intensity) of training over longer periods of time. Not necessarily a week of this or that. If your regular weekly swim distance=wsd, and then wbd and wrd respectively, then I was thinking more on the line of 1/2 - 3/4 wsd & wcd, and 2x wrd or vice versa over a period of a month or two or perhaps even longer. To some degree you could even work in annual cycles.
The reason for this working is that when you reach a certain level of fitness/perforamnce it is far easier to maintain it or regain than to get there in the first place. Hence by placing more bias on each discipline for a while you can progress to higher levels than you would otherwise in those disciplines and then maintain that level on lower levels of training while progressing in other discplines.
As to what the levels/percentages/equations are, I don't know. Triathlon has been more theory than practice for me of late...
And key to good tumble turns is the head. When you tuck teh head down keep tucking and then kepping tucking some more. Where most newbies go wrong is that they push/tuck the head and then stop pushing and so progression of the turn stops. The head LEADS the way. Keep tucking the head under and the body follows more easily. Just watch out for your feet on the side as you over shooy when you first get it right! - it makes such a difference.
