There seems to be a plague of people who triple tongue this way..
TA-KA-TA, TA-KA-TA, TA-KA-TA
I ask them why. The usual response: I don't know. I've just always done it that way. Nobody ever told me how.
You should use..
Why do we multiple tongue at all?
Because you can't reset the tip of the tongue fast enough over and over.
Here's my contention (argue if you want): the second of the two "TA's" is the weaker one because the tongue has to do that rapid reset.
Test this: say TA-ta. Now say ta-TA . (capital letters represent emphasis).
For me, TA-ta is easier.
So...the whole point of using that inferior "KA" syllable is to give the tip of the tongue time to reset.
In a string of triplets, you usually want to place your accent on the first note of each triplet..
TA-ta-ka, TA-ta-ka, TA-ta-ka
Putting ka at the end makes it easier to emphasize the beginning of the triplet.
If you use..
TA-ka-ta, TA-ka-ta, TA-ka-ta,
your downbeats will be at a disadvantage.
(By the way, in the new Arban's book, both Bowman and Alessi prefer ta-ta-ka)
If you are used to the other way, use this exercise to help you...