Tablets update themselves within a few minutes of a new release. A tablet on an old version is usually switched off or asleep. Restart asks every tablet at that school to reload the next time it checks in; nobody's records change. A school can't set up more tablets than it is allowed (1 unless set here); tablets already working are never switched off by the limit. Block is for emergencies, such as a stolen tablet: the school sees "Blocked by SchoolGo" and your reason, and records are kept.