The Block Date feature is less relevant for PTC, as you typically won’t schedule conferences on public holidays or similar dates. This page mainly serves as a review, allowing you to see which dates the school has marked as Block Dates.
If a PTC date has been marked as a Block Date — which would prevent activities from being scheduled on that day — you should untick the “Use Organisation Block Date” option at the container level to allow the PTC to proceed.
See this article for more information