In my experience many Excel solutions are business unit driven where I and other developers are brought in when it becomes untenable to keep Excel as the solution. As can be expected the common issues are too many concurrent users (some would say more than one is too many), data protection requirements, regulatory and legal compliance, central control of systems and data, central enforcement of minimal standards for application support (e.g. data backup, source control, availability, disaster recovery etc.).

Many of these Excel based solutions have been reasonably accurate, however, most have resolved some erroneous data issues. Some of which have been financial in nature. Having said that this continuous cycle of business units developing Excel solutions and their replacement with managed applications probably means that the financial skew of a any business with this model of application development is almost a constant. If the skew isn't too great or the business too fiscally weak then I can imagine that it is probably only out as much as any large business' accounts.

I would not say the same for financial institutes or financial service companies. Here a skew is likely to be disproportionate to the finances of the business by comparison.