More engines (4 vs 2) and bigger inlets mean more multiple engine strikes.
The pilot workload goes up when multiple engines are involved.
When you involve more than one engine it implies a flock encounter and in that case the flocking bird-species behaviour (ball flocks vs flying V's, etc.) significantly affect the data. Birds are not inaminate objects to be sucked into engines. They do have avoidance manuevers based on visuals and noise, so the number of strikes does not correlate directly with inlet area but rather a rough correlation with diameter