First they needed to be bright enough to do the spectral analysis. So there might be some bias in the results. Certainly red giants would be poor choices when looking for planetary transits. I believe the best approach is to identify candidates with a survey and use another telescope, like an LX200, to follow the candidates for long periods of time to see if other tansits occur. If so the number .015 would not apply to the general population of stars.
Transits are periodic.
We should be able to take advantage of this. If you detect parts of a transit on different periods it as good as getting multiple observations of the same transit. The only way you could hope to do that would be to pick a few small fields and hit them every night. Also and maybe more importantly, a periodic signal can be detected at a much lower signal to noise ratio. Given enough data points there are many signal processing tricks that would apply.