Top: individual transit S/N for all validated KOIs (Exoplanet Archive Disposition of ‘confirmed’) or candidate (disposition of ‘candidate’) as of May 2021. Bottom: peak-to-peak TTV amplitude of Kepler planets and candidates as a function of the S/N of individual transits, for planets with TTVs of more than 3 h of peak-to-peak amplitude. Previously known systems include: Kepler-30 (Panichi et al. 2018), Kepler-88 (Nesvorný et al. 2013), KOI-227 (Nesvorný et al. 2014), Kepler-223 (Mills et al. 2016), Kepler-603 (Holczer et al. 2016), and Kepler-36 (Carter et al. 2012).