I have never seen the Brisker Rav’s position on the subject, but I can imagine him saying that Tefillin isn’t a daily chiyuv – which is, I think, the position of most Rishonim.
You are pretty much correct in your guess in general. (see below)I have no seform because I’m at work (self employed this isn’t on my bosses chesbon) but the Mishna Brura very clearly says there is a chiyuv to put on tefilin every day. I think the Mogen Avrom gives tefilin as an example of a mitzvah that has to be done daily.
Which rishonim explicitly say it isn’t a daiy chiyuv and where?
The quote I refer to is from a likut sefer that I haven’t seen in over twenty year quoting a Brisker Hagadah.(brown cover I don’t remember the name
Rav Moshe Sternbuch writes that he heard the BR held there is a chiyuv to wear tefilin every day but it isn’t a NEW chiyuv every day. It is a constant chiyuv that you are yotze by wearing them once a day.