The connection you made in your first drawing is not allowed.
But I did not complete it. I took the DEX hint and did it direct. See second drawing.
You dont seem to understand what we are talking about . The short vertical trace between pin 6 and 7 is what i am talking about. That is not allowed for the detailed reasons i listed.
Anyway you will mot learn this stuff from books , you need access to the standards from IPC and you will need tot talk to people doing board design for production. A lot of this stuff you learn by sending a design to manufacturing and having it shot down in flames. There are courses you can follow like the CID course from IPC but that is only the basics. It takes years to know all the intricacities.
There are some good courses at certain universisties like the emc course from mark montrose (which i did and aced it with top score)
Ather good books are the handbook of black magic (yes that is whats it called) and the books from the speeding edge: pcb layout done right the first time. There is emc for pcb design as well. I will post a list of the books i have laying around that deal with some of the complex stuff.
Pcb technology has evolved tremendously from when you did layout on rubylith. Accept that there is a whole bunch you do not know. That reflects on dex as well. I have listed several things that are minimum requirements to do a modern board. Stuff gets really complex once you start doing HDI boards . I just did a board that has 0402 parts with 4 mil track and gap as smallest feature and simultaneously traces that need to hold 100 ampere. Creating the structures for such currents alone is bery comex as you need to spread power vertically through the layers.
Via stitching rules for example, taking into account plating thickness , ohmic differences betwen ated and rolled copper. You cant ace voas too close together because the hole wall will warp. You need to know the weave of the material to guarantee enough strands and mot cause in hole delamination. All that stuff needs looking at and then design rules are set up so that once we start drawing we cannot violate any rule. Mechanical rules , placement rules , soldering rules. Electromagnetic rules testability rules and much more.
A good software can handle these conex rule sets and work interactively with the layouter to make sure no violations creep in.