It was not always an opening to exploit for Ash when Jason showed one.
There were always times when he tried to feint an attack by leaving an opening on purpose so that he could lure her in.
There were a couple of times when she almost got caught by him the moment that she stepped into his range.
Just like how Ash was adapting to how he fought, he was doing the same.
All he needed was one good clean hit with enough power and he could turn the fight back in his favor.
Ash kept trying to bring him down with calculated strikes toward areas that would cause the most negative effects on Jason.
Jason was enduring it and was not giving up against her.
He stubbornly kept attacking her while seeking out other methods to turn the tables on her.
The fight had only been going on for minutes yet it seemed that much longer.