The answer, and what it costs to be wrong
Our accountant reviews the statements
Ask them one question before you decide: what gross-up threshold does your lease set, and was it applied?
Reviewing the arithmetic is not reading the lease
An accountant checks that the statement adds up and that it matches what was accrued. The errors that cost money are not arithmetic: they are a denominator that excludes an anchor the lease includes, a fee on a base the clause does not allow, capital expensed instead of amortised, a cap measured from the wrong base year. Finding those means reading the lease against the statement, clause by clause.
The statement that adds up
Almost every statement adds up. That is what makes this category expensive: the total is right and the inputs are not, so nothing about the document looks wrong.
Run one site and compare
Take a site your accountant has already reviewed and scan it. If we find nothing, you have learned something useful about your accountant. If we find something, you have learned something more useful.