Sorry, I should add:
The fact that the 2nd beat is slightly early while the 3rd is played slightly late gives the impression the 2nd beat is lasting longer.
I think the important thing is to dance "one to a bar". In effect as a musician I would play/sing each bar as a disctinct beat. I would not count 1-2-3 but rather a succession of long "ones".
But as I said, I don't have enough dance experience to say how dance teachers and advanced students deal with this.
OB