The timing needs some work yes. They use a combination of several things. Random selection of enemies in range, combined with a random start time. It worked great initially. However, when I tried to balance the damage per second (e.g. fire rate), it collapsed a bit. Thanks for the suggestions, and I had several as well. But, the short amount of time I actually had to spend on this jam, meant it landed on an MVP level.
Thanks for playing Necron