You can be creative while making a cartoon, but basic art principles like scale and proportions shouldn't be changed every episode. It not a matter of unfair criticism, it's just a standard that should be followed. Keep consistency in what already exists, there's tons of room to be creative in other places like new settings, designs, movement, etc.

Can't be mistakes if they don't have a set character sheet.

In all seriousness I do love the show and generally overlook while watching episodes. But it is kinda annoying that Sugar didn't want to implement character sheets because she didn't want to "limit creativity" in storyboard artists.