Over time, I've realized that there is a great advantage for everybody implicated on a campaign when the PCs party belong to an established group in-game, with an implied goals and sometimes, even a roster for backup PCs.
On our cyberpunk campaigns, it was the gang. Everybody starting as gang members gave you a drive and an identity instantaneously, leaving your character background story for whenever you wanted (or never). You never had to think about why your character was adventuring with the rest of the party (even though you could if you wanted). Blades in the Dark is built on that, too. On the game I wrote some days ago, PCs are assumed to form a group of Vampire Hunters.
They are not as evident, but Shadowrun and OSR D&D work nice for that, too: Your character starts as a gold seeker first, background second. It is very easy to work a game with no preemptive thinking as long as you start the game in the door of the dungeon (One of the best advice I've ever heard). By the time the party has reached town/downtime, the characters and the dynamics amongst them will be fleshed out organically. The world is designed so shadowrunners/adventurers are a thing running around the setting, so restoring a lost member is an easy task for the players.
Now that I think about it, on our Naruto campaign, we started as a team of three under the tutelage of a Jonin NPC, and our master started the game during a ninja exam. It was one of my first games and I roleplayed my ninja girl trying to go home until the teacher set a trap on her hahaha.
On the opposite side, I remember the Usagi Yojimbo campaign I ran where I was fucking autistic trying to make sense of every single detail and had a session zero with all the players separatelly where we created the character, back when it wasn't called session zero yet. It was an awesome campaign that I wish I had made some kind of log. I used the old technique of putting the players on a tavern and dropping a hook and hoping they picked it. What got me in love with Pen and Paper RPGs back then was the idea of a Video Game with unbound freedom to do whatever you wanted, and if they had chose to ignore the hook and walk out the inn in the rain I was devoted to make it possible, but Im glad they didn't.
To summarize, the thesis is that the less background, and the more the characters are defined by their role instead of their personal idiosincrasy, the easier it is for the GM and players alike to start a campaing in a meaningful direction, leaving the rest for a second or third sessions where the inertia has already put the game in motion.
Crime Gangs, Esoteric Cults, Brotherhoods against a common evil and Public Officers of some kind are good examples of groups that work nicely (and D&D raiders count as crime gangs I guess). I'm set on running a fantasy game with no dungeons someday, playing into the medieval/court life part of medieval fantast, but I have trouble imagining what kind of elements for party cohesion can I make up, being that things such as a wizard doesnt fit into a group of knight retainers... IDK. Its not that its really needful: we are adults today and I can just make up missions, point my finger at the player and say: "take the hook, motherfucker" but you know, I always spend time thinking about things like that.
