Publishers remember being spammed. Two people from the same agency approaching one editor in a fortnight closes that door permanently, so a shared record of who has been contacted, when and about what is not optional.
A placement is an asset with attributes. The page, the date, what it cost, which client it was for and where the link points has to be recorded at the time, because reconstructing that a year later is impossible.
Decay has to be measured deliberately. Links removed during a site redesign or an editorial clear-out are invisible unless something rechecks them, and a client discovering that first is a client leaving.
Outreach is a numbers operation with a human face. Emails sent, replies received and placements secured show which angles work, and an agency not measuring reply rates is simply guessing at its own method.