The Doctor kept at least two volumes of time logs.
The Fourth Doctor hinted he was too busy to still keep track of his travels, indicating that he had written them earlier in the present incarnation, or in an earlier one altogether.
He asked Adric to search the logs for references to previous travels to Traken. Adric managed to read the language of the journal, even if he was hindered by the Doctor's handwriting and by the lack of chronological and logical order. The Alzarian expressed frustration with the log by exclaiming, "I read about something that's just happened. The next page says it didn't happen at all!" (TV: The Keeper of Traken)