Now where was I? Ah, yes...
Probably one of the most important things that I learnt from the
Commandos is when to switch off. When we were not required to do
our thing, we were absolute sloths ( I remember being almost two
hours ahead of schedule for a LRRP deployment once - we stopped in
the middle of a pile of dense vegetation, laid down a groundsheet
and had a few games of blackjack
).
More importantly, we learned never to take unnecessary risks -
there would be enough time for risk-taking when the action
started.
Admittedly, one risk I took that did not pay off was upon
enlistment. I was not a particularly enthusiastic enlistee, and
going into the vocational interview, I had a rather stern-looking
sergeant ask me, "So, do you want to go into Commandos?". Hoping to
show him an attitude that he would disapprove of, I asked him if I
had a choice and when he said no, I said, "So what the f*** are you
asking me for?". I only found out to my chagrin over the next two
and a half years that this was exactly the attitude they were
looking for. 
Once again dragging myself back to the topic, I will try to address
your question of how one comes up with a formula to determine what
constitutes calculated risks and what constitutes
recklessness.
I think that there are two key differences between risk-taking and
recklessness. First, there is the amount of preparation involved. I
had no real problem with parachuting because the ground training
over two weeks more than made sure we knew the drill and that we
checked and double-checked everything. I would be leery of taking a
civilian course where the training is covered over the space of a
few hours, and where the safety procedures and preparation are, in
my opinion at least, inadequate.
The other difference lies in the reason for taking the risk. If
there is no reason to take a risk, it does become something of an
indulgence. Coming back to Lee's reference to motor sports, the
best comeback I can provide to that is to quote three-time Formula
1 world champion Sir Jack Brabham: "I never drive any faster than
it takes to win a race.". If you already comfortably leading a
race, why push the car so hard that you could end up breaking
something and losing the race? On the other hand, if you are
lagging behind, you may as well push it and see what happens.
There is a third factor which is something of an interaction
between the first two - how much of a risk do you take? The
masochist in me loves being in a tight corner, because I can then
play it like I have nothing to lose because, well, I have nothing
to lose. However, if the situation is comfortable, I tend to avoid
shifting the pieces that are already in place - there is no point
in wrecking things when I have no need to. To take a risk for the
simple sake of it, to get an adrenaline rush, is the opposite end
of the scale to "kiasuism"; one approach is as mindless as the
other, and both equally lack function.
To tie all of this back to the topic of Remaking Singapore, the
problem here is that in Singaporean society, you are expected to
not rock the boat - yes sir, no sir, three bags full is the way to
go, and independent thought tends to get you marked as a loose
cannon on deck. Obnoxious, recalcitrant gits like yours truly
generally persist on doing things their own way, but speaking from
experience, that does not make life easy for them in Singapore.
When they decide that they have had enough and find greener
pastures, where their ability to come up with fresh ideas is
encouraged, the government labels them quitters. The sad reality is
that Singapore is set up to drive away the people best equipped to
take the country into the league into which its economy has
grown.
On the other hand, we would not be well served by the knee jerk
reaction of tying to go to the other end of the scale. That is like
plunging a freezing man into boiling water. Certainly, Singaporeans
need to be less timid than they are presently, but going back to
the equation I cited above, if one were to consider taking a risk,
a few questions need to be asked:
1. What stands to be lost if the risk was not taken?
2. What stands to be lost if the risk is taken?
3. How do 1 and 2 weigh up against each other?
4. What proportion of the risk is controllable?
5. What backup measures are there should things not go according to
plan?
If the loss is greater when the risk is not taken, and if there are
measures already in place to control the situation if things go
wrong, by all means go ahead and take the risk. But if there is no
point to it, i.e. the answer to 1 is of too low a value, taking the
risk would not be the smartest thing to do.
In the situation against the Guardsmen, the recommended course of
action in training, if you remember your BMT, would have been
either to execute an ambush drill or to fall back in leapfrogging
pairs. Because we were outnumbered almost three to one, either
course of action would not have had good results for us - in the
case of falling back in pairs, we would have effectively been
outnumbered five to one. My calculation at the time was that they
saw four of us and could not know how many had gone behind the bush
ahead of us. From my experiences with Guardsmen (this was my third
exercise against them), I expected them to know the drill as well
as I did, which meant that doing the tried and tested was something
they would likely have been ready for. Again from my experience,
the drawback of the Guardsmen was that they rarely deviated from
the drill, and I was prepared to take the risk that the Guards'
leader would not think as I did. Upon these considerations, I
decided to propose this plan to my team, and it worked. It
therefore fit the definition of a calculated risk.
A true calculated risk will most likely not match the average
person's definition of a risk. The philosophy behind taking a
calculated risk is to ensure that the cards are stacked firmly in
your favour. Gather as much knowledge of the situation as you can
and work out the process so clearly that you can see it happening.
Fortune does not so much favour the bold as it does the bold and
prepared. A calculated risk is not a question of going, "If I do
this, then this will happen, and then this will happen.". Instead,
it would be more like "If I do this, these two things might happen.
In case of the first event, I can do this, and in case of the
second event, I can do that", and so on and so forth, following a
branching structure that covers all possible contingencies.
In the case of parachuting, the sequence would be, "If I look up
and see a fully open canopy, everything is fine and I can prepare
for a landing. However, if I look up and see a partially open
canopy, I cover my reserve, pull the ripcord, grab the reserve
canopy and throw it out in front of me as far as I can so that it
does not get tangled in the main canopy. On the other hand, if I
see no canopy at all, I just pull the ripcord. If nothing works, I
grab my ankles, pull my legs up to my chest and kiss my precious
ass goodbye.". 
Well, you get the idea - cover all contingencies before you decide
to do something where the outcome is not given. That is a
calculated risk.