The database is the business, and most firms are quietly destroying theirs
A staffing firm competitive advantage is a pool of people who answer when it calls. That pool is destroyed by exactly one thing: sending everybody everything. It happens gradually. A consultant under pressure blasts a requirement to two thousand contacts, gets four replies, and concludes it worked. What actually happened is that a few hundred good candidates decided this firm sends irrelevant jobs and stopped reading, and nobody will ever measure that.
So the routine here is as much about restraint as reach. Fewer, better matched, clearly reasoned contacts. A database where the availability data is current. And a hard limit on how often any individual hears from the firm, enforced across consultants rather than left to each desk.