However, manual effects can be played expressively and easily timed to coincide with the script. Sampled SFX, while real, are often hard to manipulate with precision. I love manual SFX even for airplanes, thunder, and wind, but some sounds are difficult to fake manually. I used a Kurzweil sampler with a Peavey trigger pad and faders for each sound. For sound effects of short duration gunshots, electric sparks, explosions the samples were easy to cue to the script.
Short samples work well with live-style production.
For SFX of long duration fire engines wailing and pulling up, a jet plane passing overhead the timing was unreliable. The actor then resumed speaking and ended his speech just as the fire engines pulled up. But in front of the live audience, the actor rushed his entrance and his lines. So, the trucks would pull up way too late, creating nearly-dead air. We faded out the trucks before they arrived, to allow the next live music cue to start and get us to the next scene.