Fridge Logic: They almost never actually prevent the life-destroying events that led the targets into their current crises.
The ending of the season 4 episode Flights Of Angels (aired in 1998). To clarify, the Character Of The Day Richard has ALS, better known as Lou Gehrig's disease. The doctors never give him the medicine introduced by the FDA in 1996 to treat the disease, and when their family is all together his wife does not call 911 (the emergency telephone number was introduced in 1968) to get medical help to save his life. There was no reason why he shouldn't have lived.