If previous eruptions had left Mount St. Helens with a different shape, what differences might have influenced the timing of the eruption?

Different shapes of volcanoes will influence the timing of the eruption because they have a different type of pressure.

Volcanoes with tighter entrance will have higher pressure built up within it and the eruption that came from of it tend to be louder and faster.

Meanwhile, volcanoes with bigger entrance have lower pressure in it, so the eruption that came from it tend to be slower.