Many years ago when I first started teaching ASL -- the standard answer to
the question of how many handshapes were used in the fingerspelled ABC's was 22.
The idea was that the 26 letters of the alphabet were represented by just 22
handshapes (with duplicates for I / J, G / Q, K/P, H/U).
These days that seems really silly to anyone who has actually studied
fingerspelling at the frame by frame level. When you dissect hundreds of videos
of real life fingerspelled words frame by frame you will note numerous versions
of the handshapes often varying depending on the shapes of the nearby letters.
(Co-articulatory effects.)
Often when a teacher (or a "teacher" -- visualize air quotes) tells you "this is
the right way" to sign something -- what they are actually showing you "the
citation" version, a dictionary version, the version their teacher taught them,
or what they would show an "ASL 1" class -- but not necessarily what shows up on
Deaf hands in real conversation.
If your fingerspelling reaches a level where your fingers start exhibiting
transitory variations and some well-meaning person corrects you I recommend you
just "thank you" -- (and then move on with your life). The better you get and
more you know -- the more often certain people (who consider themselves to be
authorities) will correct you when you don't need correcting but rather you are
using a version that the other person is unfamiliar with.
Instead of letting your ego get hurt I suggest you simply think of it as, "Okay,
now I have one more vote for this other way" -- and then put that sign on your
radar so you can gather more and more votes to help you decide if you really do
need to change your signing in some way.
There is an old joke in the interpreting world:
How many terps does it take to change a light bulb?
Three.
One to change the bulb and two to stand there and comment on how they would have
done it differently.
Notes:
More info, see:
https://www.lifeprint.com/asl101/topics/lexicalization.htm
Also see: https://youtu.be/SATsyIl_C_Q