Exxon Mobil Card does have certain limits regarding the accumulation of rewards. Generally, there are thresholds for how many points can be earned within a specified time period. For example, there may be an annual cap on the number of rewards points that a user can accumulate, which can vary based on the specific rewards program in effect. Additionally, rewards points may have expiration dates, meaning they may need to be used within a certain timeframe after being earned. It is always advisable for users to regularly check the details of the rewards program on the official Exxon Mobil website. There, users can find the most accurate and up-to-date information regarding limits and any changes to the rewards structure that may have occurred.