The follow-up routine most firms run on memory
A proposal leaves a partner inbox on a Tuesday. Nothing is written down beyond the sent folder. Whether it is chased on day four or day forty depends on whether that partner had a quiet fortnight, and a client waiting on a board date looks exactly like a client who has gone elsewhere.
The cost is not dramatic and that is why it survives. It shows up as proposals that were never formally declined, referral sources who stopped introducing work because nobody thanked them, and past clients rebought from the open market at full acquisition cost because no one noticed the relationship had gone quiet.
