Colour bias is an attribute, not a habit.
Lets consider their definitions according to websters dictionary.
habit [hab-it]
Example Sentences Origin
hab·it1 [hab-it] Show IPA
noun
1.
an acquired behavior pattern regularly followed until it has become almost involuntary: the habit of looking both ways before crossing the street.
2.
customary practice or use: Daily bathing is an American habit.
3.
a particular practice, custom, or usage: the habit of shaking hands.
4.
a dominant or regular disposition or tendency; prevailing character or quality: She has a habit of looking at the bright side of things.
5.
addiction, especially to narcotics (often preceded by the ).
at·trib·ute [v. uh-trib-yoot; n. a-truh-byoot] Show IPA verb, -ut·ed, -ut·ing, noun
verb (used with object)
1.
to regard as resulting from a specified cause; consider as caused by something indicated (usually followed by to ): She attributed his bad temper to ill health.
2.
to consider as a quality or characteristic of the person, thing, group, etc., indicated: He attributed intelligence to his colleagues.
3.
to consider as made by the one indicated, especially with strong evidence but in the absence of conclusive proof: to attribute a painting to an artist.
4.
to regard as produced by or originating in the time, period, place, etc., indicated; credit; assign: to attribute a work to a particular period; to attribute a discovery to a particular country.
noun
It is both, it is a habit that can be attributed to multitude of factors including simply lack of knowledge that doing all colors is more optimal than doing one color first.