You can backtrack whilst remaining inside a continent, however, some restrictions apply. For example, you can only travel from the west coast of the US to the east coast once, but you may backtrack as long as you don’t make your way back to the coast. Bear in mind that backtracking is counted in your mileage should you be purchasing a mileage-based ticket.
Round the World Airfares can also construct an itinerary to achieve almost any routing, we combine point to point fares (ticketed separately) but within the overall itinerary to achieve some incredibly unique and complex journeys.