My Favorite workflow is to do all my planning at home on my desktop/big screen computer. I like Rever (Pro) for this. Pro (paid) version gets me all the Butler maps including the BDR's.
So on Rever.co (not .com) I light up all the Butler maps rated roads, paved mountain trails, lost highways, featured dirt roads. Then I light up the campgrounds, or gas stations, or lodging or food.
I can then just start dropping points on the roads I want to ride. If the dirt track is so remote that Rever won't snap to the line/trail I just click on the pencil button and draw lines over it until I get back to a stronger trail/road, and then resume dropping crumbs that snap to the road.
I do this right on top of the Butler highlighted roads, lost highways, featured dirt roads, etc. Hit save and I'm done. No uploading to a device if I am going to navigate from a phone. It's just magically already there on my phone.
I do however usually download the .gpx to my desktop, plug in my Garmin VI and just drag the file from my desktop into the Garmin. Done now with the tracks on my Garmin, and backed up on my phone Rever app in case my Garmin craps out.
I vastly prefer navigating by the Garmin over the phone for a couple reasons. Garmin is MUCH easier for me to see due to its screen and due to it's location on the bike. . . . . and I can use the wonder wheel to zoom in and out while riding.
I once drew out a route that put my group on 26 Butler maps Gold, Red and Orange roads in one day. I think it was about 250 miles of scenic, super twisty goodness.
It was easy to do with Rever. And super easy to share with other riders that had Rever on their phones.
It really is fantastically easy to use and effective. I'd like to try Gaia and Scenic as both are also fantastic. I just am not motivated to learn a different app since Rever works so dang well and partners perfectly with the Gamin. The Pro version is worth every darn cent.