Warren
Thanks
Many of these routes are commonly used so there are permanent anchors in place. These can be used after careful inspection. Other places you may have to set up your own anchor and you need to carry sufficient gear to be able to do that. It is critically important on a route with multiple rappels as after the first rappel you have not choice but to continue down canyon and you better have the right stuff to make sure you can continue
You need to be very rigorous as the consequences are very high

Peter