I couldn't get the answer in game so I thought i'd ask you guys.
I am using the following rotation on longer fights (bosses):
VT, SW:P, DP, MB, MF, MF, etc.
The talent "Pain and Suffering" allows us only to use SW:P once per boss fight. So when I dot SW:P I only have 1 stack of Shadow Weaving on myself. What I wanna know is that when I refresh the SW:P just as it is about to run out, do I refresh the weak SW:P (with 1 stack of SW) or does it make it stronger (considering I have 5 stacks of SW at the time). Cos if not I should definetly re-dot it to have better ticks.
The MF refresh does not update buffs such as Shadow Weaving... what this means is that SW:P will tick at a level of damage for the buffs you had at the time of casting, ie. if you cast SW:P with 0 SW stacks, it will tick the entire time as though you have 0 SW stacks.
The only exception to this is that MF will refresh temp SP bonuses, be it from trinkets, racials or procs...
So, what you should be doing is start with the following rotation...
MF, VT, MB , DP, SW:P
MF is currently bugged and provides 2 stacks of Shadow Weaving, VT will place a 3rd, MB 4th , DP your 5th... then you can cast SW:P once and it will get the full benifit of your self buffs... if you have a mage in your raid that is providing imp scorch or winter's chill you should ensure that buff is at full stacks b4 casting SW:P.
The alternative is to start with sW:P and then recast it once full buffs are present but to do so will cost you a GCD and mana... personally it's not worth doing in 99.9% of circumstances but i'll leave the decision to yourself.
I use a small circuit of VT, DP, VE, SW, MF(1), SW:P to open on bosses. Not only does SW:P benefit from SW, but it does from other class buffs/debuffs aswell. Casting dots and VE during the open gives more time for other class abilities to stack their buffs for SW:P. I never cast any damaging spells right off in case it will cause any unnecessary threat.