Once over lightly typically describes a quick, superficial examination or review of something. Antonyms for this phrase could include a thorough or detailed analysis or inspection. Other antonyms might include an in-depth study or examination, a careful and meticulous review, or a comprehensive and detailed evaluation. In contrast to a once-over-lightly approach, these antonyms would emphasize the importance of taking time to fully understand and explore a subject or topic, rather than simply glossing over it. Whether in business, academia, or everyday life, taking a more thoughtful and thorough approach can often lead to better outcomes, deeper understanding, and more fulfilling experiences overall.