I've tried a few different strategies:
- Going left instead of right. It seems like the enemies don't get behind you so easily this way. But my brain doesn't like it.
- Going fast and clearing each horizontal row at a time. This works to a point, but around wave 3, the other row shots become incredibly accurate.
- Going slow and trying to shoot each trio is the best option for me. Try to keep them from getting behind you. Once you get to 40k or so, things start moving very fast. There's no time limit, so moving very slow has no real downside.
In all cases, keeping your eye on the radar is key.