Let me a bit more precise on this request: I mean anywhere where there is a reasonable location, i.e. a pad, via or already existing trace, so that Eagle knows what signal is being picked up fpr routing.
When routing traces on the PCB, one can only start routing where a rubber band/air wire starts. Quite often I find this bahavior coutner productive, as I would like to begin routing at some via on one end of the new trace, but the rubber band has attached itself to the closest location of another trace already routed to the end location. Therefore I am forced to begin routing at the inconvenient end. This is particularly troublsome when routing SMD devices with ICs where the pitch does not agree with the routing grid (which is practically always the case). To hit the IC pads exactly, one has to start routing at those pads. Often I find myself forced to rip up part of a trace, just so I can start routing where I need to.
Also it happens quite a bit that I would like to route an alternate track that seems to work out better, but only want to rip up the original trace once I get the new trace in and know that it works out. Same thing here, I have to rip up the original at least partly to be able to do any routing at all.
This restriction really gets in the way of productive work.