Does fifteen minutes of DSA on the train actually add up to anything

Full time job, ninety minute round trip commute, that's basically the only consistent block I have most days. Phone app, one problem, often interrupted by my stop. Compared to the two-hour weekend sessions I used to do before I had less time, it feels like it shouldn't count for much. But I've noticed patterns clicking faster than they used to. Anyone actually tracked whether short-and-constant beats long-and-rare over a few months?