One or two minutes every day will do more for you than forty minutes once a week. The long sit sounds serious and is mostly a good way to end up dreading it.

What the research says

A registered report on mental contrasting with implementation intentions found that applying it daily, rather than as a single training session, supported goal pursuit more efficiently. A Cochrane review of oral naltrexone shows the other half of the point in a very different setting: the medication did what it does pharmacologically, and it still failed in practice because people stopped taking it. Neither study is about meditation dosing, so what carries over is only the pattern that a thing helps while it is still being done.

Strength of evidence: one line of research. A single study, or a theoretical account.