Adventure framework

I'm not a very experienced referee. I've run about five adventures, three of which were one-shots. I've mostly used premade materials.

Traveller lends itself extremely well to sandbox campaigns. The UWP, the sector maps, the economy, everything is designed for long running campaigns.

However, I'm curious, what frameworks do you guys use to design adventures that last a couple or a few sessions that tie your campaigns together? Do you start slow? Do you throw them in the medias res? How you plan for the different skills to shine? How do you plan for the number of sessions?

I realize it varies from adventure to adventure and from group to group, but are there formulas or frameworks for any of this?

There are so many great random tables, from patrons to encounters, but I don't have enough experience to tie it all in together for a few-session-adventure. Curious if people have any kind of system they use.