I have upgraded my operating system several times now and routinely have to rebuild my local working environment because the update blows away everything in /usr. Is this just ignorance on my part? Should I have created a /usr partition along with /home? Additionally, because /usr is mounted as / and several of my codes want to install to /usr/local I found that the 20 GB of the / partition was being exhausted.
I am now toiling away as before in 13.2 but would appreciate any advice before 13.x and 14.y come along.
From your story, it seems that you have a lot in /usr/local ad that that is what you loose. Not to difficult IMHO, whenever you want to install a new openSUSE version, make a backup of /usr/local (well, you have have one anyhow of course) and restore it after the action.
Alternative, make /usr/local a separate file system (like /home). That would also cater for the fact that 20GB is not enough for / (my assumption is that you realy have several GB in /usr/local then).
If I may suggest, you could also install openSUSE on a LVM based system, on the future. This way you can resize your partitions with ease. I have my / on btrFS and openSUSE’s partitioner automatically handles subvolumes such as /usr/local. I set my / partition with 60 GiB, just in case, even though I don’t even use 20 GiB. On the future, however, this 60 GiB space will be more than appreciated, specially because I have snapshots enabled But you don’t have to set up a fixed size, you can leave the partitions just as openSUSE’s partitioner makes them, this way they are automatically resized when needed.