Most journey work stops at the signature, because that is where the marketing budget stops. What happens afterwards is filed under delivery and treated as a different discipline with a different owner.
The buyer does not experience it as two things. The confidence they arrived with, the confidence they built through the process, and the confidence they feel in the first fortnight of the work are one continuous line. A drop in that line after the signature is the most expensive drop available, because the acquisition has already been paid for.
Where the line usually drops
The common failure is a change of cast. The people who were present during the decision are replaced by people who were not, and the new arrivals ask questions the buyer has already answered. Whatever the delivery quality turns out to be, the opening impression is that the firm did not read its own notes.
The second failure is a change of register. The sales process promised precision and the delivery process opens with a generic kickoff deck. The buyer concludes that the precision was a sales artefact, and they are usually right.
Why it pays back
Referral and reactivation are the cheapest sources of work any firm has, and both are produced almost entirely by the first six weeks of delivery. A journey design that treats those weeks as part of the commercial system rather than as the start of an operational one is treating the cheapest pipeline in the business as though it mattered.
This is also where a reformation is most often abandoned, because the second half of the journey belongs to whoever runs delivery, and they were not in the room when the first half was redesigned.