Maybe it is just me, but there seems to be a difference between how Traveller handles random encounters versus other games. Of course, I realize as I am typing this that I am conflating 76 Patrons with random encounters.
For fantasy random encounters, depending on what sort of fantasy you have, you can have all sorts of encounters from the mundane to the fantastical. Reading a bit, and saw that, at least for dungeons, each level lower had harder encounters. Not having actually played a lot of D&D back in the day (Traveller mostly!) and not playing many dungeon crawlers now, I never noticed that. It is a simple metric and, depending on the game, a resource management system.
Traveller encounters, on the other hand, are really broken into 2 broad categories: animal encounters and NPC encounters. Animal encounters are yet another game system that breaks it down into ecosphere and has a lot of rules to make a reasonable (for some definition of reasonable!) set of possible encounters based on the landscape you are in. Some basic reaction rolls, and you can see how this looks like a monster compendium. In fact - I use the Heaven and Earth program (still running almost 30 years later!) and it will generate all the animal encounters you could want. A world will have as many animal encounter tables as there are biospheres. Possibly dozens of animal encounter tables.
Have I ever used those tables? Not really: the worlds I create I tend to do some bespoke encounters specific for that world that I want to be in the game. However, years later now, I can see some games where this does become important. There's an interesting discussion on COTI about Safari ships, and I can see running a safari-style game. And in a SF world, most animals are not a threat as you sail over them in your air/raft or level an over-powered gauss rifle at them. For me, the animal encounters (which could encompass geophysical encounters as well) just were not used a lot.
The NPC random encounters came in 3 flavors: a plain random encounter table, the basic starship encounter table, and the patrons encounter table.
The NPC encounter list you can see coming from previous fantasy games:
We're playing an SF game and encounter - peasants with clubs and cudgels! Merchants with daggers! Guards with halberds!
Well, I actually have used this table and it is always funny. Of course, Traveller goes cover a wide range of technology. And a lot of early Traveller was based on pulpy SF where these types of encoutners fit right in. If I had the time and inclination overlapping, I'd generate random encounter tables per world per area. Failing that, a broader set for all worlds based on both the technology, world stats and government types. I can see an entire book devoted to creating encounter tables based on various factors. In fact, Supplement 7 did that, with expanded encounter tables that had some location-based factors (XBoat) but mostly DMs based on things like how many parsecs the next world was at.
Where the meat of encounters in Traveller is, though, is in the patrons. Fantasy games have patrons - in some systems magic users need patrons to learn spells and things. And I've been messing around with guilds and cults which can also be seen as patrons as well as good game hooks. But in Traveller, the 76 Patrons book ranked right up there as one of my favorite supplements. The base plot given, then a few possibilities for what was really there. I used that book quite a lot when I was running way back. I've not directly used it in my recent games. The primary reason was that the last few games I did have an over-reaching idea of what we were doing.
Where these encounter tables work best is the long-running campaign: you need to come up with ideas and these encounter books help. What I am learning though is that you need to run the tables before the game: set up a few things ahead of time. I may be old, but I am still learning.
The Cowboy & Dinosaur game came to a somewhat fizzled-out conclusion. It is in a good place, and we can take it back up again, though I do need to make wanted posters for all of them. They killed off John Chisum. Yes, he had been sending out men to mess with the Pawnee and take their lands, but there was nothing the law was aware of. Technically the group are now murderers and may start to get the law after them. But I started getting tired of running the game, and 10 sessions is a pretty good stretch for me. There were no random encounters other than the ones I was building. Some of those came from player ideas (yes, they saw a Sasquatch!) but the majority were created from the Apex book and I feel I started lacking enough imagination to carry that on. Or at least imagination for running an old West game. And part of that is I also felt somewhat constrained to keep things a bit historical. Though there were dinosaurs, and I did introduce the Center of the Earth as a possibility as well! So I may have started straying from 1885 Utah. Sadly, I never did Mormons in, though I did have one of the rancher's family dying from dysentery. I'll post an update at some point for that, as there were several random encounters I marked on the map.
With the 76 Patrons book, the Starport encounters book, and plus really liking to play and run Traveller, I probably could run a Traveller game a good long time. I can have random encounters there that have more impact than I was getting with the cowboy game. Make up worlds. In fact, if we can get the group to play, even though there is no XP per se, what I'd love to do is go through character creation per player, then have them roll up their home world and describe that. We'd create our own OTU and expand from there. I know at least one player would love that, the others may. It would just take a bit more time to do that. And while two of us are really into world-building, not sure how much the others are.
Same for a fantasy game running in my worlds: I feel like I can plop in anything I want to, and strange encounters would work well. And I must have dozens of PDFs and a few actual books full of random things like that. So many possibilities!
And finally: the encounters should all show a living world. Old West, fantasy, Traveller or other SF: these encounters show the world is doing things outside of the players. I keep saying that, and I feel I am not doing well at that particular part of world building. That is - after world building comes the living world. And I think that will be worth a post sometime soon!