I see Shadowrun as a TV series with seasons and red threats per season. Structuring it that way really helped me offer different scenarios and engage personal backgrounds while still keeping a central plot hidden underneath the waves. Works perfectly like a campaign that way. Think Supernatural or Blacklist.
Shadowrun does have the advantage that it's more friendly to one-shots than for example D&D. With D&D, often the bigger adventures people set up are really focused at long-term involvement, or might even demand someone play multiple sessions in a row due to being in the middle of a dungeon crawl. With Shadowrun, the end goal is set from the start and each session can be run individually. At the start, you get offered a job. At the end, you hope you're still alive and that you'll get paid somehow. Much easier to close a case or explain why a random person is there one run and not the next.