If your slug case more as one event , then you have a force/time exicite
(maybe harmonic).
And then you become higher DLF, because your system go in Resonanz.
For a harmonic damped system :
DLF = 1/ SQRT (( 1- fe/fn)*(1-fe/fn)+ 4 D*D * fe/fn)

fe ==> your ecitite frequency
fn ==> natural frequency
D ==> Damping (%)