The spread may be used once every twelve weeks or four times in one calendar year; at intervals of twelve weeks on the average.
As the name goes Tree of Life spread is holistic interpretation of all of you, as best as you can understand. If you do the first Tree of Life tarot reading, in for example, the month of august, it is assumed that by the next August of the next calendar year you will have done the fourth Tree of Life reading, if you so desire. Opt for Tree of Life tarot spread any time of your choice, if that works for you.