Believe you are confused with your terms.
An LOI is not a counter.
You can have more than 25 LOIs in a year. However, the final number of Grant in Aids a school issues is limited to 25 per year. This is NOT determined on LOI day, as some might expect. The date may vary, but it is linked to the opening of full summer practice for a school. At that point, you can only have a maximum of 25 scholarships in an given year.
If an individual's scholarship gets applied to a previous year, it is the granting of the Scholarship that triggers the year, not the LOI.
As noted in a previous post, the number of LOIs a school may issue in one year, may be limited by conference rules. So, it can vary by conference.