With my whacking-great cast of characters I've had to create a complex database and spreadsheets to keep track of details such as descriptions, skills, jobs, kids' names, relationships, cars, weapons etc so I can quickly look them up when I need them (rather than flicking back an unknown number of pages just to keep the type of car they're driving consistent throughout the work. (Would be embarrassing if they parked a Mitsubishi and then, ten pages later, drove off in a Mazda. Fuck, I knew
it started with an "M", dammit!)
I've found that a number of them are currently rather superficial but I'm sure they will flesh out over the course of the story.
I've had to have that many characters to avoid having a small group of people all with an improbably high number of areas of expertise and experience way beyond their years as well as a superhuman capacity to get all sorts of shit done in record time while still tending to the basics and managing to stop to eat and rest.
In addition to those around whom the story centres there are others who I've mapped out as they get mentioned from time to time - "historical" references and occasional visits or assistance and I need to keep their skills etc consistent.
The relationship map is getting rather complicated as they interact, too, and I'm having to keep track of how they get on with one another.
I did a lot of initial work (once I realised I was going to need a tribe) creating the characters and filling in as many blanks as possible in the database but I can see the database being added to as things grow out of the work and the situations reveal more about the characters. Also, as they develop, the database is going to have to change to reflect that. There's already a living/deceased field, the status of which will change for some characters.
I also instinctively put them into Cast Herds
before I had even heard of the trope - it was the only logical way to keep things manageable. However, it's not just one or two "spokesmen" from each herd that interact with the others. Anyone from any herd can and will turn up and have their own unique interactions with other characters from other herds.
My big difficulty, when I've got a large-ish herd and referring to what they're doing, is to avoid situations like the page quote for Loads and Loads of Characters
where it starts reading like the Mouseketeer Roll Call. Finding other ways of saying "Catherine, Andrea, Helen, Artur, Bettina and I sat outside having cigarettes and coffee with Malcolm, Joanne, Sheree and Cassie", that aren't as cumbersome, can be a pain. I deeply feel that "all of us except Bryan went outside to check out the noise" is putting too much on the reader to remember which of the huge cast of characters were present prior to that point. Easy to do visually on TV or a movie as the viewer can see at a glance who's there but a lot harder when the list of players in that scene may have been last added to three pages ago.