The agamas say that we should not worship the Perumal in the sanctum sanctorum on Pradosham. It is our duty to perform aradhanam for Bhagavan, as per the agamas. Going by this, not worshipping the Perumal at the sanctum sanctorum at temple is also a duty to Bhagavan. As pradosham period is a period for Srinrusimha Perumal, agamas allow worshipping him at temples.
Since mahapradosham period is the time of Rudra tandavam, we are to be silent at homes during this period. This is a type of kainkaryam (service) to Perumal. Elders take vows before entering a period of silence, which is a type of fasting (mouna vratam).
One and half hours before and after sunset is the pradosha period.