Most FF programs allow some routing through different regions, but it depends on the origin and destination, and what routing you want to do. US-EUR-Middle East or US-Middle East-East Asia are almost always allowed. "Backtracking" as you suggest (US-EUR via middle east, for example) is less common.

as there are dozens of programs, and dozens of possible routings, i think more specific question or searching "routing rules" might be a good idea.