I have a red controller that has programmable rapid fire. I had to replace the bottom of the shell at some point. anyway, iirc, it will flash the bottom left quadrant in the ring of light, then it flashes every time you change timings. I think there are 7 levels. it's just been a long time since I've used it.Very few will make such trainers.
As far as limited compared to a trainer then stick some kind of teensy or whatever nice programmable chips exist out there and you can make it fire in whatever timings or patterns you so desire.