The Rambam paskens that there is a mitzvah d'orasya to daven once a day every day. Ramban disagrees and holds that md'oraysa one is only obligated to daven during a time of crisis and need, not every day.
Rav Soloveitchik explained that the Rambam does not disagree with the fundamental premis that tefilah is a response to crisis; what he disagreed with is the Ramban's conclusion that therefore tefilah need not be recited daily. According to the Rambam, man is situated in an existential state of crisis from which he turns to G-d to to seek relief from on a daily basis.
I have always liked this explanation of the Rav, but it occured to me that it does not take into account the Ramban's comment on "mikra'ei kodesh," where he says that tefilah b'tzibur is part of the d'orasya mitzvah of celebrating Yom Tov. Prayer can be a song of joy as well as a plea for relief from suffering. Perhaps the Rambam held of an even brighter picture of life and thought that the joy of prayer should be celebrated every day and not just on those few mikra'ei kodesh of the year. From the picture of the Rav's personality that I have formed in my mind from reading his writings I can easily see why he offered the explanation he did as opposed to the one I am suggesting here. (Does the fact that I thought of this idea now mean my personality is changing? I don't think so : )
Perhaps one can distinguish between the tefilah of the individual, which is a response to crisis, and the tefilah of Yamim Tovim, where the Ramban makes a point of saying that celebration is done through communal prayer.