It would seem the quarter hours flights and then half hour flights are more likely than the on-hour flights to be cancelled. Other predictors may include day of the week (predicted demand). I’m not sure you can tell outside 24hrs how likely a flight is to get dropped - seat selection tools or availability tools don’t brilliantly predict load ((selection may reflect “who’s chosen yet” and availability is a max of 9/7 per travel class - although a wide open all fare bucket flight may be in danger but it’s not a certainty as you don’t know the loading in the other direction / next flight of the day).
Beyond the quarter hour flights, I think it’s too dynamic to predict with any reliability.