I don't actually have the charts Vololiberista so can only go by the flight plan given me by P3D. I recognise myself that sometimes they're crazy and do cut a few out but when I'm IFR and told to fly by my own navigation, whats left is all I've got to go by.
I could fly VFR and cut out more of the routes but that usually creates more problems when I finally get close to the destination airport.
John
Go onto
https://skyvector.com/ Enter the origin and destination ICAO codes. Skyvector will draw a point to point line. Then all you need to do is type in the waypoints one by one with a space in between, press return and skyvector will automatically find them. That way you will see the airways and whether they are correct or not. Also if the flightplanning software tries to find airways when they are not required you can see that too and delete the offending waypoints and add the correct ones. Skyvector is always up to date with regard to airac cycles. As is online flight planner.
Another point with regard to BIG is that it is a major hold for London Heathrow from FL70 upwards so if you were to fly there you would have to be at FL60 when passing. My suggested route to DVR avoids the traffic on the inbound STAR and also SIDs that use BIG as they too are constrained to FL60. So it's best to stay out of their way!