Schlesinger's hands-off attitude toward his animators allowed Freleng and his fellow directors almost complete creative control and room to experiment with cartoon comedy styles, which allowed the studio to kept pace with the Disney studio's technical superiority. Freleng's style quickly matured, and he became a master of
comic timing. He also introduced or redesigned a number of famous Warner characters, including
Yosemite Sam in 1945, the cat-and-bird duo,
Sylvester and
Tweety in 1947, and
Speedy Gonzales in 1955.
Freleng and
Chuck Jones would dominate the Warner Bros. studio in the years after
World War II, Freleng largely concentrating on the above mentioned characters and
Bugs Bunny. Nearly all of the Bugs Bunny cartoons pitting the rabbit against Yosemite Sam in various historical time periods were directed by Freleng, plus some of Bugs' cartoons with Elmer Fudd and/or Daffy Duck or with gangsters Rocky and Mugsy.
Freleng also directed cartoons with the Goofy Gophers (most notably those with the polite rodents trying to retrieve their natural property in a processing factory), cartoons with Sylvester being pursued by a pair of dogs, Spike and Chester, several of the cartoons involving a drunken stork, a number of cartoons in which insects act in military unison to battle a human character, cartoons with characters Daffy Duck or Yosemite Sam marrying for money, and three cartoons, with Bugs Bunny, Sylvester, Tweety, that spoof "
The Strange Case of Dr. Jekyll and Mr. Hyde".
Freleng also continued to produce modernized versions of the musical comedies he animated in his early career, such as
The Three Little Bops (1957) and
Pizzacato Pussycat (1955). Freleng won four Oscars during his time at Warner Bros., for the films
Tweetie Pie (1947),
Speedy Gonzales (1955),
Knighty Knight Bugs (1958) and
Birds Anonymous (1957). And other Freleng cartoons such as
Sandy Claws (1955),
Mexicali Shmoes (1959),
Mouse and Garden (1960), and
The Pied Piper of Guadalupe (1961) were Oscar nominees.