[Gollum]

The art of stepping backward and forward is also taught in my karate style (gojuryu shoreikan). We do have an entire kiso kumite on that purpose (kiso kumite dai ion) as well as several other exercises (wapu, hojoundo dai ni, etc.).

It is crucial to be able to get in reach when striking and to immediately get out of reach when defending. This is the whole purpose of footwork (suri-ashi, yuri-ashi and so on)...

Now, as said by Kromm, you do not necessarily have to cover a full yard. But, for gaming purpose, it is more convenient to use a full hexe because doing so allows to simulate the possibility for the attacker to force the defender who retreats while dodging to go backward and, eventually, to corner him.

Did you see some Mike Tyson’s combats? He was so good with dodge without stepping back that he almost systematically forced his opponents to go backward until they were cornered. Which means that they did step back while dodging or parrying.