The time used depends on the way in which the client reflects and articulates their memories. Some are faster than others, some need to “ruminate” ideas more than others (5 in the Enneagram are usually slower “thinkers”).
The facilitator can speed up the process, properly, by inviting them to move forward.
The technique in the session can also be used by asking only for 4 – 5 memories, and do the technique like that. Afterwards, you can give the client the task of “continuing” with the pillars at home, doing it as an exercise of reflection, meditation and gratitude for life. This would also give a theme for the next session.