As long as all the processes are on the same machine the wal mode is a good idea. It's not good in the case where multiple machines are sharing the same databa

As long as all the processes are on the same machine the wal mode is a good idea. It's not good in the case where multiple machines are sharing the same database. Like say if you had a shared settings file which allowed multiple VMs to be set in one place. Obviously the same-machine situation is the most common. But you asked for a reason for when wal is not appropriate.