This is why I think you should drop counting 5,6,7 and 8 in a 4/4 measure:
1. There simply isn´t 5,6,7,8 in a 4/4 feel. A 4/4 measure only consists of 4 beats. Namely: one, two, three and four.
2. It is totally f***ing 80s and sounds a little stupid anyways. Who started it? Fame? :)
3.Counting to 8 ignores a main fact of swing music, which is a strong feel for the 4 beats. Ask Basie he knows : "Four beats and no messin´", Count Basie.
4. Since by pure logic 1 is not 5 and 2 is not 6 and 3 is not 7 and 4 is not 8, this whole concept is pretty confusing.
5. Transfering this way of "wrong" counting to other measures like 3/4 would mean trouble, because then you would end up counting a 6/4 or 6/8 which is clearly different than a 3/4 feel.
6. You probably count a 3/4 or 5/4 measure correct but not a simple 4/4? WTF???
7. Once you get used to correct counting you always know were you are in the music and you are able to communicate it with other musicians who also "speak the language". This is a universal musical language, that makes sense. Why do you want as dancer stand out, and simply do it wrong?
8.You will never ever have to translate your steps and choreography when trying to work with musicians.... (How many eights again????) Stop being confused when trying to arrange your dancing to music.
9. It´s a first step towards thinking in musical terms as a dancer and understanding the music. And since most (tap) dancers claim to be musicians that should be a given.
10. Become a happy (tap) dancer.