The following are my observations as a public sector planner.
In general, we have noticed certain components of our consultants' work contain recycled ideas and text. In general though, I don't think that had affected the quality of the final product.
In one specific case, we actually wanted our consultant to use recycled ideas. We seeked out that particular consultant because of their track record of using their very innovative concept to solve problems under other comparable circumstances.
We have also seen a few bad examples:
1. We did a very innovative plan almost 20 years ago. It was a rather lengthy plan for a community of over 90,000. It included not only the traditional land use policies, but contained a lot of economic and social policies. Within a year or so, we came across a consultant's draft plan for a rural community with a populatioon of perhaps in the 5,000 - 10,000 range, whose name I had never heard of. It was an exact carbon copy except for the land use component, of course. Well they say "Imitation is ....". I guess we should feel very flattered.
2. In an economic development strategy study, the consultant borrowed Richard Florida's concepts. In their initial presentation to Council, the presentation didn't even mention Florida's name once. And even though the final report did footnoted his name, it did not contain any usefull specific recommendation on how our city could implement Florida's ideas other than generic recommendations such as "support arts and culture, etc.".
3. But I think the worst case was when our municipality (and several other municipalities elsewhere in the province) were forced to amalgamate into "megacities" by the province. The amalgamation report prepared for our community contained the name of another previously amalgamated municipality (on. p. 47, as I remember). I guess the "search and replace" function on their word processor didn't work perfectly.