Here's my data from WWS. Sadly, I don't have much more as I just upgraded to T5 shoulders and lost the bonus (we also lost a few WWS logs in the meantime).
Len is the length of the fight in minutes, as measured by WWS DPS time (I know it's not perfect, but it's a good measure of the time I spend casting rather than running away from stuff).
Hit is the number of spells that hit (resists don't matter for procing the bonus).
Shadowflame/flameshadow are the number of times each proced. Total is the combined number of procs.
Proc% is the number of procs divided by the number of hits. PPM is the number of procs divided by the length of the fight.
len hit shadowflame flameshadow total %proc ppm
9 177 0 5 5 0.03 0.56
8 136 1 4 5 0.04 0.63
6 122 2 5 7 0.06 1.17
5 103 0 3 3 0.03 0.6
8 164 2 8 10 0.06 1.25
6 114 0 3 3 0.03 0.5
14 216 0 6 6 0.03 0.43
9 153 0 9 9 0.06 1
6 116 0 5 5 0.04 0.83
EDIT: I've excluded Tidewalker and Hydross specifically because we use AoE those fights and it's practically impossible to tell how many SoC's were cast by just looking at a WWS parse.