MRCP(UK) applies a limit to the number of Part 1 attempts, and candidates who reach that limit must satisfy additional requirements before applying again. Because attempt rules are reviewed from time to time, confirm the current limit with MRCP(UK) rather than relying on advice from previous cohorts.
If you are re-sitting, the practical constraint is the calendar: with three diets a year and a one-week application window, a failed attempt usually means the next realistic sitting is about four months later. Use the interval to work through your incorrect and flagged questions rather than restarting revision from the beginning.