It was the third time the company tried to implement SAP's products. I think I may have been one of the very few people who worked on all three attempts. The winning recipe was having a business owner who threw up his hands at the failed efforts to get a larger scoped company-wide project underway and "selfishly" declared that the finance dept would do it for its own benefits. And he tooks his best people out of their day jobs, put them on the project team, and made them move offices to sit in the same open plan war-rooms as the IT staff (which took some doing...Microsoft was pretty much all unshared private offices at that time) I think we reduced the time it took to "close the books" each month from something like 3 weeks to under one week.
And we absolutely changed the business to meet the way the software worked, that's one of the key success factors for implementing any ERP software. Your "unique requirements" for fixed assets accounting and accounts payable processes are not what makes your company successful, but they are what will tank your ERP implementation if you let them.
It was a fascinating project. I especially enjoyed some of the travel to implement it in the subsidiaries, where the really big business wins were. Most of the subs didn't even have a "purchase order" process (they just paid invoices, and had no idea of their outstanding commitments) or any automation around things like employee expense reports. And we got to come up with some decent creative solutions to things like Brazil's requirements for hyperinflationary accounting, without breaking the software.
Fun fact, Concur's expense reporting business was borne out of the Microsoft R/3 implementation -- some of the best consultants and developers took what they built for Microsoft's internal expense reporting and turned it into Concur's expense reporting product.