It really depends what you mean by "low". It's certainly possible at the hundreds-per-day type volume. The key is to just look for bigger effects. If 200 people show up, 10/100 convert on A, and 25/100 convert on B then B wins (p < .01)
As your traffic scales, you can look for smaller and smaller effects. But the whole idea of testing variants can be applied pretty damn early.
As your traffic scales, you can look for smaller and smaller effects. But the whole idea of testing variants can be applied pretty damn early.