Alex – the figure 8’s are part of the PG pattern, and this established pattern goes to what Tim said about reasonable expectations of what the other pilots in the air are doing – this pattern is on our site briefings, should be getting taught to all students, and should be described anytime you’re giving a visiting pilot an in-person site briefing.
Not sure if you fly HG or PG, but PGs can’t nose down to lose altitude (not in a meaningful way, anyway – we’re not talking about speedbar or rapid descent techniques, as those are not advised close to the ground). We get “bumped” all the time, since thermals tend to kick off all over the LZ and especially in the approach area. The “box” that’s formed by the fence, the house, and the road give the PGs a safe area to perform sweeping turns (figure 8s) as they bring themselves down to the proper height to make their final approach to land. This is not a crutch but a simple and safe way of dealing with the reality of our wings and the weather.