I find when counting one-ansel-adams, two-ansel adams, etc, that the accuracy of my timing is well within acceptable limits...actually I tend to count slow, if anything, so that helps to take care of some of the RFailure.
Of course what one considers acceptable limits will vary a bit.
Or if you prefer, "one-mortenson, two-mortenson, three-mortenson, four-mortenson, et al"
“Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”
Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2