PIP award dates

I'm aware that there should be a 'review' date on the PIP award letter, which is generally implemented (rather than the actual award dates.) I'm wondering however, if the tribunal award letter doesn't show a review date, but just the award dates (including both dates) would the review date have to adhere to the dates on the letter ?
I am of course aware that they can review at any time, but apparently as a claimant we are able to challenge such a review unless there have been any substantial changes in the condition.
I found the following information on a disability website .......
So although a PIP review can be done at any time during the duration of a PIP award, it would seem that there should be some justification for it, either because new information has been received, or because of a change in law. Although far from being clear, it would seem that the decision to review a PIP claim could be legally challenged, if there is no basis for the review, and if there is reason to believe that DWP is punishing or harassing a claimant who has, for example, made a complaint. As it has not been tested in court, it is difficult to be certain, but the bottom line is that claimants should know that their PIP claim will be systematically reviewed one year before the end of their award. This information should be clearly mentioned in the letter they received informing them of the duration of their award. And they should challenge DWP if no review date has been mentioned in their letter but they are called for a review.
Thanks in advance for any guidance on this.