This pattern is used to say that something is not significant enough or does not meet the standard to be considered as the category mentioned. It often carries a nuance of 'it's not even worth calling ~' or 'it doesn't really count as ~'. For example, if you study only a little, you might say that doesn't count as studying. It can also be used with nouns like 'work' or 'meal' to express that something is too trivial to be considered as such.

In everyday conversation, this pattern is fairly common but tends to be used in evaluative statements. It is not overly formal, but it does have a slightly analytical tone, so it might appear more in written texts or thoughtful speech rather than casual chit-chat. The phrase literally means 'it doesn't enter into ~', suggesting that the thing is outside the boundary of that category.

Note that when using with a noun, you need to use the particle の before うち. For verbs, you attach the plain form directly without any particle.