Do you have specific requirement for the pulse length? if not, please use the default signal, which is optimized. In particular, for linear simulation, no need to change the pulse length, except you want to have narrow bandwidth or there is resonance outside the desired bandwidth that prevents fast convergence.
Only when you want time-domain, accumulate effect then you need to set the pulse length to be practical, which is rare.
For nonlinear simulation, it might be different, depending on what the nonlinear effect you simulate. In some case you have to use almost sine excitation: https://optics.ansys.com/hc/en-us/articles/360042192813