Most of the firms I work with run on people who come and go. A consultancy staffs engagements with contractors. A brokerage has a dozen staff and a hundred independent agents. A law firm brings in contract attorneys and paralegals for a busy season. Each of them needs to learn how the firm works, and the faster they do, the sooner they're worth what you're paying them.
Each of them is also someone you've just met. You're right to be careful about what they can see. Your client list isn't theirs to browse, and neither are the internal documents that happen to sit next to the ones they need.
The usual answer, and what it costs
So most firms do the sensible thing: least access. A new contractor gets the minimum, and more is granted when they ask for it and can show a need. Security people recommend it for good reason. It limits what can leak, and it means every permission has a reason behind it.
It also has a cost nobody writes down. A contractor can't ask for what they don't know exists. They don't know there's a checklist for the thing they're doing, or that the firm settled this exact question last spring, or who to ask about the part that's unusual. So they guess, or they interrupt whoever sits nearest, or they quietly do it their own way. Ramp-up that should take days takes months, and some people never get there before the engagement ends.
The firm ends up choosing between two bad options: open the shared drive and hope, or lock it down and accept the slow start.
Two kinds of knowledge
The way out is to notice that "what a contractor needs" is really two different things.
How the firm works. The process for opening a matter, the steps in a listing appointment, the standard for a client deliverable, who signs off on what, what to do when a deal wobbles. This is what a contractor needs to contribute, and almost none of it is sensitive. It's the firm's way of doing things, and you want everyone doing it that way.
What the firm holds. Client names, contact details, financials, the case files, the pipeline, the internal documents about the business itself. A contractor needs a slice of this for their own work, and nothing more.
In most firms the two are mixed together in the same folders, the same wiki, the same people's heads. That's why access has to be all or nothing: you can't hand over the process without handing over the records sitting beside it.
Separate them, and the dilemma goes away. Least access to records, full access to process. The process goes to everyone on day one. The records stay behind the permissions you already manage, granted the way they are today.
What that looks like in practice
Write down how your firm works, in plain language, apart from any client's details. Start from what's already written: the checklists, policies and templates people use. For each kind of work, ask how you'd know it was done well, and write that down too. Keep it current as the firm's way of doing things changes. Put it somewhere every person can reach the day they start, and make sure their access ends when they leave.
That last part matters as much as the first. A process guide that former contractors can still read isn't a leak of client data, but it is your firm's way of working, walking out the door.
How we do it
This is most of what we do for firms, and it starts with listening. We sit down with the people who know how the work goes and ask them to describe it in plain language: how a typical piece of work runs, where it goes wrong, the case that still keeps them up at night.
We also ask for what's already written down, as much as they're comfortable sharing: a checklist, a policy, a template, an onboarding document. And for every piece of work we ask the question that finds the rest: how do you know it was done well? There's usually an answer. A golden example everyone points new people to, a checklist someone runs before anything goes out, a partner who reviews the first few. That quality control is often the most valuable knowledge a firm has, and it's rarely written down in one place.
Sometimes the best version of it lives inside a real case: the closing checklist from one particular deal, the review notes on one client's deliverable. When it does, we sanitize it. Client names and details come out, the reusable part stays, and only that clean version goes into the guide. An automated scan then blocks things like account numbers and Social Security numbers outright before anything ships, and a person reviews for the rest.
Every contractor can ask the guide from day one, from the Claude or ChatGPT account they already have, or from our iPhone app, which keeps the guide on the phone so it works without signal. When someone leaves, an owner or manager removes them, and their access ends at once. The copy on their phone stops working at its next check-in, and it can't go more than a week without one.
The questions the guide couldn't answer come back to the firm, so the next contractor finds the answer the last one had to ask for. That's the part that compounds: every person who ramps up makes the next one faster.