Let me make a simple question un-simple.
Like many things in Astrology, the answer is both simple and not so simple.
Let us start with how we treat a major aspect between two planets. If we are talking two outer planets, we consider two cases. First, a conjunction or opposition is generally given a single degree of 'orb' or pronounced influence. Second, because the planets move so slowly it is possible to discern a 'cyclic' effect where in the influence builds up in quiet but persistent ways. We can use Saturn conjoining natal Mars as an example. Saturn will dampen the natural expression (for an individual) of Mars' energy for the several days it contacts Mars. As a cyclic effect, it may teach one to use more self-discipline in the use of Mars -- it may test this lesson at the quarter cycles and opposition points. Because of Saturn's long orbital process, this may be a lesson that is forgotten about over time.
Let us now look at a fast moving 'planet', the Moon relative to the Sun (with the Earth in a special role). As a full Moon, which you asked about, the Moon may trigger a reaction when it is within a couple of degrees of being full. If we allow only one degree, we are talking a two hour window of time. But, because the Moon is a constant and predominate influence, we are attuned to it and will actually feel it sooner and longer than a two hour period.
Now, we need to consider other Astrological applications. When working with midpoints and progressed or directed charts, we find that accuracy within just a few minutes of a degree will relate to a trigger or eventful date or a period of just a few days.
When working with Return charts, the Moon can be given several degrees of orb because we mostly care about the 'day' within the Return chart's cycle. We also introduce the angles of the Return chart as the effective zones, so we would be looking for the Moon transiting an angle. The Moon or other planet is effective at the angles of a Return chart.
The type of Return chart is also important to consider. A lunar return chart focuses upon 'reactions, emotions, habits, routine, empathy and family issues'. As such a transit to any planet in the Return chart will-or-may trigger something in the subject's chart related to those matters. In a Saturn-Return chart, it becomes another matter. WE HAVE TO ALWAYS CONSIDER what role the two planets involved are doing in the natal chart. If they are active together in the natal chart, they will likely also interact in a transiting chart. If they do not interact in the natal chart, they are likely to ignore each other in a transiting chart.
So, it comes down to 1) what are you looking for, 2) what type of chart are you using, 3) how long is the cycle relative to the transit-within-an-orb-of-contact, 4) what is the role of the involved planets in the natal chart? Astrology is an art of synthesis. We blend subtle things within a whole sense, details within broad themes. Sometimes we have a mosaic of details, sometimes we find on things is enough to consider. It's simple, its complicated.
Perhaps you should cite a specific and detailed example so that the question and answer can be narrowed down.