I dont think so that it need to get very hot to be effective - however it also perform good when it get very hot -
As these are designed for the purpose to reduce heat - thats why even after repeated hard stops it performs better.
When cold, ceramic brakes may squeek but once it warms up, it works fine even in city routine driving.
But as you said that its useless in everyday driving - YES, there is no need of it in normal conditions but @JZ always do experiments, so lets wait for the result 