The phrase "cover all bases" generally means to thoroughly address and prepare for all possible scenarios. Antonyms for this phrase would be to "take shortcuts" or "cut corners", meaning to not fully address all possible outcomes and instead take easier or faster routes. Another antonym could be "ignoring possibilities", which means to disregard potential problems or situations that could arise. Lastly, "half-hearted attempts" could be an antonym for "cover all bases", suggesting a lack of effort or dedication in preparing for possible outcomes. Overall, the antonyms suggest a lack of thoroughness and preparation.