Currently in Live Accounts (July 2013) the Pay Centre tries to be convenient by updating its start/finish dates and some oter details based on the last pay run. This works OK if you only have one pay frequency. However, if you have some employees that are paid fortnightly and others that are paid monthly, then the situation is more complex.
It would be useful if the Pay Centre retained its details by Pay Frequency. That is, when you select (say) "Fortnightly" the Pay Centre updates to reflect the last fortnightly pay run and the next expected fortnightly pay run. It could also pre-select the last group of employees paid fortnightly. Alternatively, if you change the selection to "Monthly" the Pay Centre updates to reflet the last monthly pay run and the next expected monthly pay run and the last group of employees paid monthly.