I have pregenerated Spring, Summer, Fall, and Winter weather results, and encounter tables for different regions. I get watches, etc. from the party. I describe the area, in brief, and the weather, and roll for possible encounters. Rolls of "no encounter" don't occur, but instead point to another table, which lists encounters with stray cows, pets, etc., in civilised lands, or birds, rabbits, maybe even a deer sighting, in wilder areas. PCs are free to ignore the common critters, or try to find the owner of Bessie, the wandering Milch-Cow, if they like. Often, the "uninteresting" wild encounters turn into a hunting expedition.
Entire (very memorable) adventures have been rolled as random encounters, with my players just SURE that it was all an integral part of the deeper mystery of my story... And pretty much every thing, except the critter stats, was winged!

Like the time the high-level (10th) PCs encountered a lone Werewolf... He was in Human form, dressed in mere leather armor (as, back in those days, Lycanthropes took damage when changing in better armor). He was watching this obviously-powerful group, and was spotted by the Elven Druid on watch, who threw
Entangle. Trapped, he was surrounded and questioned. Fearing
Detect Lies, and the like, he quickly determined to stick as close to the absolute truth as was Humanly (or Werewolf-ly) possible, so rightly claimed to be a hunter who lived in these woods...
This was made more memorable by my casually assuming a mock-ozzie accent, and playing this bit part to the hilt. The PCs questioned him, then fed him, and finally let him go... When one of the PCs later disappeared (his player having done the same), the remaining players were just SURE that the scruffy little "hunter" must have somehow been involved! They spent hours worth of game-time on this one episode, trying to figure out what happened to their missing friend, and never even realized that it was a random encounter!
