Recently, Tony Cox posted:

I've had a smoldering dispute with a CFI friend of mine for
years about whether to announce (say) "zero-two" or just
"two" when operating at an uncontrolled field with runways
2-20. My friend is of the opinion that the extra "zero" is
superfluous, whereas I've always instinctively said "zero-two"
without really understanding why I do it. It has always "just
seemed right", with a blank in the orderly transmission of
information that cried out to be filled.

This weekend I felt vindicated. As I started to taxi out at
0L7 (two runways, 2-20R and 2-20L), I was not particularly
surprised to hear a Cherokee doing touch-and-gos on runway 2 (the
wind was 5 out of the north). Listening to several calls as I
prepared to depart, I finally caught a "two-zero" -- the fellow,
out of exuberance or lack of currency was letting his finger
slip off the transmit button to give an entirely erroneous and
completely believable false impression of what he was up to.
Turns out he was practicing downwind landings. Add to that
that the airport is right traffic for 20 and left for 02, the
potential for disaster is evident.

So what do instructors teach these days? Do you add the
extra zero or not?

At some point, common sense has to play a part in what you say or omit. I
believe that it is important to eliminate ambiguity, so in the case of
runways that have the potential for confusion, as is the case with "two"
vs. "two zero", I would do as you did, and say "zero two". Note that in
either case, the potential for losing part of the transmission exists, and
if so, the same ambiguity is created as before. But, at least you've done
what you can to reduce the ambiguity.

Neil