It's interesting because I typically play the opposite way, I go exploring and adventuring and get around to a main quest when I'm in the area or something.
Starfield I've just played on an ad hoc basis - which mission is of interest right now?
The other night I was doing a main storyline quest when I got a distress call in space - random side quest. Went and did it and it was a fantastic little story arc with nothing to do with anything, just a well written side quest with some fun and a bit of loot at the end. That's my preferred way of playing, the wayward adventure out to see what's what.