Off-road routing is direct join the dots routing, requiring a waypoint on every junction, just about. You would use this method if you don't have routing on the GPS itself.
If you use follow road routing, you don't need a waypoint anything like so often. It's still best not to have them too far apart, as there's more scope for the routing on the GPS to take you a different way than the routing on the PC did. I'd put one every time the route deviated from a straightish line, or where there was an adjacent route I definitely didn't want to take.
I'd suggest using car or delivery rather than bicycle. Bicycle routes are often not the shortest, which makes it a bit difficult to predict where they will go. There is fairly obviously something in there about trying to avoid major roads, and it's very handy when you want to navigate into a strange town, but if you wanted to be sure to take a particular route you'd have to put a lot of waypoints in.
My settings are:
Guidance method: prompted (I chose follow road almost always)
Follow road method: prompted (shortest usually chosen)
Off Route Calculation: automatic
Calculation method: best route (can be slow if your waypoints are a long way apart)
Calculate routes for: car (switch to bicycle for foreign cities)
Avoid: Highways, U-turns (avoid U-turns so I can deviate off the programmed route without being nagged to turn round)
If you put a waypoint on every junction, the settings will be mostly irrelevant, and the only difference between off-road and follow road will be that the highlighted route will follow the actual road rather than going directly to the next waypoint (with consequent more accurate distances/ETAs). The only exception would be if your route went the wrong way up a 1-way street.
