Uh-huh. Because they're all lesser than him anyway (save for Dooku who's a match for him), so what's Vaapad going to do for him there? It only scales him to the level of the opponent he's up against, or in other words nothing if those opponents are already weaker than or equal to him. As was the case with everyone he fought until Palpatine.
So he more or less just relied on his own skill in those fights. Which makes sense given he routed Ventress pretty quickly and matched Dooku.