(Note: I searched the group before posting and although there are several questions about habits, none are asking about this specific point. This is close, but it's not the same (and it's framed so as to allow personal opinions which I'm expressly not (here) interested in. So this is not, as far as I can see, a duplicate.)
Do the Buddhist texts say anything that could resolve the apparent tension between on the one hand the mindfulness involved in the paying attention to every passing moment that is part and parcel of a lot of meditation practice, especially Vipassana, and the useful mindlessness of even a good habit, whereby we train ourselves to do certain things without having to consciously pay attention?
There is a growing amount of modern writing on habits and habituation, covering both the scientific and theoretical aspects of the underlying brain correlates, and also the practical life-affecting aspects relevant to the challenge of how to form useful habits and break problematic ones (e.g. Duhigg, Babauta). And that's not just recent material. Here's a condensed section from William James, written in 1890, dealing with that practical side.
The general opinion of such writers is that (good) habits are a Good Thing, specifically because they lower the load on our limited brains by making certain decisions--Shall I floss my teeth? Shall I go out for a run? Shall I sit down to meditate? and so on--more or less automatic, and as a result let us focus our limited non-automatic "will power" where it is most needed.
But the whole basis of habits seems to be the development of a kind of mind-less-ness, and that sounds fundamentally opposed to the mind-ful-ness needed for much of meditation. One possible way of resolving the apparent conflict would be to see habits as useful for establishing the boundaries that exist between the various activities throughout our day, but not for use within the activity itself. In other words, we make the act of sitting down to meditate as mindless/automatic as possible, but we then meditate mindfully.
But then that too could be at odds with the view that over time what began as an occasional mindful state should eventually become just our constant state of being, so that we were effectively meditating all the time. Presumably at that advanced level there no longer are any habituated boundaries, and everything is under awareness.
Perhaps the answer is that habits are to be seen merely as a learner's "prop"; training wheels we use until such times as we have no need of them because by then the elephant has become docile, the monkey and rabbit have departed, and we have finally reached our goal.
So what, if anything, do the established writings say about this?
To stress: although I've no doubt there are lots of good opinions out there (and for sure there are indeed lots of opinions!), I'm looking for answers with some backup from a source--old or current, either is fine--with at least a modicum of reliability. So the suttas and commentaries, obviously, but anything else of reasonable authorship including the modern.