Francis de Sales was a writer and so he is patron of journalists and writers.
Clare of Assisi was named patron of television because one Christmas when she was too ill to leave her bed she saw and heard Christmas Mass -- even though it was taking place miles away. A patron saint can help us when we follow the example of that saint's life and when we ask for that saint's intercessory prayers to God. The official Roman calendar of feast days for celebration by the Universal Church (in other words, all over the world) does not have a saint's feast day every day.
That doesn't mean that other saints are somehow less holy -- although some of the saints that have been dropped were legendary and there is little evidence they existed.
As a matter of fact, this practice came from a long-standing tradition in the Jewish faith of honoring prophets and holy people with shrines.
The first saints were martyrs, people who had given up their lives for the Faith in the persecution of Christians.
For example, many people ask Saint Monica to pray for them if they have trouble with unanswered prayers, because Monica prayed for twenty years for her son to be converted.
Finally her prayers were answered in a way she never dreamed of -- her son, Augustine, became a canonized saint and a Doctor of the Church.