It is very clear to me that there are more advantages to setting the back bars into the linings as opposed to removing the lining in that area and glueing a support under the bar. Firstly there is an extra step involved in using a separate support. Secondly those supports are difficult to shape after the fact (the top ones are easy to shape with a bellied chisel if you are putting the top on first and then the back). The last disadvantage has to do with glue squeeze out. A pocket makes a very self contained joint whereas the open lining with the support is open and allows glue flow if you are not very careful, especially if the brace end is high. And that is the problem, I use supports for the back bars on my Torres copies because that is what he did but also because with those unscallopped bars the bar end is too high to allow a pocket with enough support.