Full body weight hangboard training or pull-ups are way too intense for me to build or maintain route endurance.
To extend the time under tension to the length experienced on a route and to practice resting as is needed in route climbing I suggest a modification: chair pull-ups, but using the hangboard or other training holds.*
- it lets you stay on the holds much longer, as you would on a route
- you work pulling muscles at an intensity that is realistic for route climbing
- a slight backward incline is more realistic than a plumb free-hang
- you can offload enough weight onto your feet to shake out and recover
- full-body workout: you work your arms and legs simultaneously
You can move the chair (or other support) around to vary the intensity and work different positions, all the way to body rows.
I feel it is important to work your entire body at once, i.e. upper and lower body in the same exercise, as this is inherent in climbing and there are aspects of endurance that are specific to the muscle groups being worked.
* For endurance I like sloper holds like Bombs, as these are kinder to the fingers and seem to work the hands and forearms more completely.