Reaction tables aren't (in my view) about reducing GM workload in generating content. They're an action resolution tool (if the players declare an action like *We greet the <NPCs>") or a framing/stakes tool (if the PCs are thrust into an encounter with some NPCs).
Treasure tables, and random encounter tables, do help generate content. I've found the Classic Traveller encounter tables helpful in play. I think the rules text isn't quite as clear as it could be, though. Here is the starship and on-world encounter text from Classic Traveller (1997 ed; Book 3, p 19; Book 2, p 36):
Non-player characters are frequently encountered by travellers in the course of their adventures. Such persons are manipulated or controlled by the referee; their actions and deeds influence and direct the activities of the actual player-characters in the game.
Encounters with non-player characters are of three general types: ordinary or routine encounters, random encounters, and encounters with patrons. When an encounter occurs, the identity or occupation of the encountered person or group is determined, their reaction to the adventurers is noted from the reaction table, and the players then indicate their activity in response.
Encounters with non-player characters serve as a vehicle for direction and input by the referee. They can offer information or assistance if their reaction is appropriate. They can hinder or redirect adventurers through the use of threat or violence. Encounters also serve as a method for players to gain comrades, weapons, vehicles or assistance where necessary. . .
RANDOM ENCOUNTERS
Adventurers, as they travel about on planets, also have random encounters with an unpredictable variety of individuals or groups. Such individuals are themselves performing various tasks, which may complement, supplement, oppose, or be irrelevant to, the goals of the adventurers themselves.
Some random encounters are mandated by the referee. For example, a band may encounter a guard patrol at a building while in the course of visiting (or burglarizing) it. The referee is always free to impose encounters to further the cause of the adventure being played; in many cases, he actually has a responsibility to do so.
Other random encounters are dictated by the random encounter process. Usually, a random encounter point with humans will occur once per day. There is a one third chance that a group will be met (throw one die: a result of 5 or 6 indicates an encounter). Encounters with persons are independent of the procedure for encounters with animals described in the animal encounter section.
When a ship enters a star system, there is a chance that any one of a variety of ships will be encountered. The ship encounter table is used to determine the specific type of vessel which is met. This result may, and should, be superseded by the referee in specific situations, especially if a newly entered system is in military or civil turmoil, or involves other circumstances.
Encounters with non-player characters are of three general types: ordinary or routine encounters, random encounters, and encounters with patrons. When an encounter occurs, the identity or occupation of the encountered person or group is determined, their reaction to the adventurers is noted from the reaction table, and the players then indicate their activity in response.
Encounters with non-player characters serve as a vehicle for direction and input by the referee. They can offer information or assistance if their reaction is appropriate. They can hinder or redirect adventurers through the use of threat or violence. Encounters also serve as a method for players to gain comrades, weapons, vehicles or assistance where necessary. . .
RANDOM ENCOUNTERS
Adventurers, as they travel about on planets, also have random encounters with an unpredictable variety of individuals or groups. Such individuals are themselves performing various tasks, which may complement, supplement, oppose, or be irrelevant to, the goals of the adventurers themselves.
Some random encounters are mandated by the referee. For example, a band may encounter a guard patrol at a building while in the course of visiting (or burglarizing) it. The referee is always free to impose encounters to further the cause of the adventure being played; in many cases, he actually has a responsibility to do so.
Other random encounters are dictated by the random encounter process. Usually, a random encounter point with humans will occur once per day. There is a one third chance that a group will be met (throw one die: a result of 5 or 6 indicates an encounter). Encounters with persons are independent of the procedure for encounters with animals described in the animal encounter section.
When a ship enters a star system, there is a chance that any one of a variety of ships will be encountered. The ship encounter table is used to determine the specific type of vessel which is met. This result may, and should, be superseded by the referee in specific situations, especially if a newly entered system is in military or civil turmoil, or involves other circumstances.
This rules text moves between an in-fiction perspective (eg "individuals . . . performing various tasks, which may <be in various relations to> the goals of the adventurers") and a GM-decision-making perspective (eg "in many cases, <the referee> actually has a responsibility to <impose encounters>"). The last of the quoted sentences, dealing with starship encounters, manages to shift from the latter to the former perspective within the one sentence. But there is no real discussion of how the GM establishes "the adventure being played" or "if a newly entered system is in . . . turmoil", and how these random encounters relate to that (eg can they be input into that sort of decision-making?).
One thing that I think characterises modern rulebooks is greater clarity about how these sorts of tables work, and how the events/situations that they generate are meant to be incorporated by the GM. For me, again, Torchbearer 2e is a really good example.
