Thinking about it, adding crossovers doesn't make sense
to the 10-min rule! 
All I see them doing is add 1 crossover here, 1 crossover there,
but no fleet addition of any sort. In fact, when TIB 0793C left the
S307 fleet for WLDEP, it has been assumed its a fleet reduction for
S307 instead without any replacement. 
For this case, you wait probably lesser than 10 minutes for the
bus during the timeframe 3.30pm to 6.00pm, but after that, there's
no more.
And something I would like to clarify. Does the 10 minute rule
only apply to PM
peak? How about AM
peak? Means I still might have to wait 10 minutes and above
during weekday mornings. 
About S969 getting an addition of 1 bus, most likely there
wasn't. They took 1 main Split duty off to cross to S812. 
So people at Tampines complaining
more?
Looking at how SBST handles this, we do see fleet additions, no?
S325 gets additional Split, S315 is getting theirs too... these
cater to BOTH the AM and PM peak, hence they do satisfy the
requirements of the 10-min rule...
Shouldn't complain too much, heehee... adding some trips is
better than NOTHING.
Let me help you enlighten why some services (812 for this case)
need PM Peak xovers but not AM Peak.
During AM Peak, all perm buses of the service are out in full
force - the A S1 and S2 shifts. Break times are minimal and the
frequency is met.
However, during PM Peak, the variable factor to consider is the
P shift BC/SL's Meal Break. They tend to occur just before and
during PM Peak period.
Assuming run time & frequency (i.e. 10min) during peak hours
is the same, when 1 P shift BC/SL goes for meal break during PM
Peak, another bus needs to cover it due to the adherement of the
10min frequency.
On the ground you may not feel much difference as the frequency
is about the same as AM Peak but the fact is there's an extra bus
running on the route thanks to P shift Meal Break.
And that is also the reason why many commuters find PM peak
harder to wait for a bus than AM Peak, assuming no xovers to cover
frequency for PM Peak.
That's how Meal break xover buses came about.
