More thought-out is synonymous with "well-planned," "thorough," and "carefully considered." However, there are antonyms for this phrase, which are just as vital in expressing the opposite idea. The first antonym for more thought-out is "haphazard," meaning disorganized or done without any plan. Another antonym is "impulsive," which refers to acting without thinking or planning. Similarly, "unsystematic" is another antonym that suggests lacking an organized approach or system. Additionally, "spontaneous" is another antithesis, indicating impulsiveness or acting on sudden urges. Lastly, "unplanned" is a straight opposite, characterizing activities that lack any premeditation or foresight.