I think it would be interesting if we looked at this ancient symbol from the viewpoint of the individual. Seeing this symbol, just realizing that thresholds and doorways exist and having some notion about their role in the evolutionary process we call initiation, holds much of value for us as we try to tread these paths of livingness, or discipleship, which we call our daily lives. One may think of a new threshold, not as the result or the reward of an effort, but as the effect of an effort. Results and rewards are concepts which deal with the past. Effects are more akin to new possibilities, new opportunities, new openings, all of which are by way of being thresholds.
Thresholds always deal with that which is to come, with the future.
Also, thresholds are not time constrained in anyway. We encounter the threshold in time, but it has always been there waiting for us to get to a point where we could see it. Thresholds are stations in consciousness. They signify the approach to an opening between two places in consciousness, not between two places in time at all. Thresholds are also more than the usual points of development that we know as rites of passage in a person's life.