What leaders usually conclude
The natural conclusion, reviewing the list item by item, is that integration is simply taking the normal, expected amount of time — nearly complete, with a small number of genuinely hard cases still being worked through. This reading has the advantage of being true for any single item examined in isolation, which is precisely what makes the aggregate pattern so easy to miss.
What the evidence suggests
Melissa Graebner, Koen Heimeriks, Quy Nguyen Huy, and Eero Vaara’s review of post-merger integration research, published in the Academy of Management Annals in 2017, synthesises several decades of study on how integration actually unfolds inside organisations. A consistent theme across that literature is that integration is rarely executed as a single, comprehensive decision. It proceeds instead through a long series of smaller, more localised decisions, made by different people, at different times, each responding to the specific circumstances in front of them rather than to a single coordinated integration plan.
This matters directly for how the remaining, unintegrated items in a two-years-post-acquisition organisation should actually be read. Each individual exception was, on its own terms, a reasonable localised decision — exactly the kind the research describes as the normal unit of integration activity. What the research doesn’t support is treating the accumulated total of those exceptions as similarly unremarkable. A pattern built from individually reasonable decisions, made without reference to each other, can still add up to something that nobody would have approved if it had ever been proposed as a single, aggregate choice.
The specific risk this creates is one of aggregate drift: an organisation can review each remaining integration gap in isolation, find a defensible reason for each one, and never actually ask what the combined list represents as a share of the whole operating model. By the time that question does get asked — often prompted by an external event, a new leader, or an audit — the unintegrated portion may have grown considerably larger than anyone tracking it item by item ever noticed.
Competing explanations
Not every remaining gap indicates a failure of integration discipline. Some genuinely reflect a deliberate, considered choice to preserve something that worked better unintegrated — a specific client relationship, a specialised system with no adequate replacement. The distinction worth drawing is between a gap that was deliberately preserved after an explicit evaluation, and one that simply never received that evaluation at all, having survived purely because no single moment ever forced the question.
It’s also worth distinguishing this pattern from simple slow progress. Slow integration, honestly tracked, is visible as a known, monitored backlog. The pattern described here is different specifically because each item looks resolved on its own terms — a decision was made, a reason was given — which is exactly what allows the aggregate total to grow without ever triggering the scrutiny a visible, acknowledged backlog would receive.
Where this shows up
This perspective is written with professional services firms in mind. It sits within the Professional and Knowledge-Based grouping, and the questions it raises recur in other sectors too.
Questions worth considering
- If you added up every remaining unintegrated item from your organisation’s last acquisition, what share of the current operating model would it actually represent?
- For each remaining gap, was there ever an explicit decision to leave it unintegrated — or has it simply never come up for review since the deal closed?
- Who currently owns the question of total remaining integration exposure, as opposed to the individual items that make it up?
Your team is facing similar challenges?
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