- regular, everyday walking down the street - the Japanese call this ayumiashi
- sliding, trying to keep the same foot forward -this is called tsugiashi
Ayumiashi is very energy-efficient, using only about 100kcal/hour at moderate speeds, but it has some serious problems when you're in a fight - especially when you are up close and someone has grabbed hold of you. for this sort of application, tsugiashi has some advantages, and it minimizes some of your disadvantages.
So us cool martial artists usually try to shift from ayumiashi to tsugiashi about the time we get inside touching distance (ma-ai). Notice how that shift in walking methods is encoded in the approach in each technique of Junana Hon Kata?
But have you ever noticed that kuzushi almost always forces the unbalanced player back into ayumiashi? Makes sense - we've been doing ayumiashi since childhood so we revert back to our most experienced mode when offbalanced.
Interestingly, you can look at that as one of the main goals of kuzushi - to get the other guy to shift back to ayumiashi, thus magnifying his disadvantages, thus making your opportunities greater.