So much magma is erupted that the ground surface above collapses inward to form these huge depressions. The ash and pyroclastic flows from these eruptions often are carried hundreds of km from the vent. Rhyolite complexes often have repose periods between big eruptions of hundreds of thousands of years. Some of them also experience smaler eruptions on a more frequent scale. Many of these smaller eruptions occur along the caldera boundary.
Monogenetic fields occur where the supply of magma to the surface is very low.
In these locations there is not enough magma, nor does it erupt often enough, to maintain any one preferred pathway. Many monogenetic field eruptions form cinder cones, but they also form tuff cones, maars, lava fields, or lava domes, depending on the environment they come up into and the viscosity of the erupting magma. Flood basalts are another type of volcanic eruption that fortunately we've never had to experience. They are huge volumes of basaltic lava that cover hundreds of square kilometers to depths of sometimes 200 m. The old school of thought was that these were fast-moving very thick lava flows that were emplaced in a matter of weeks to months.