I’m fairly new too, but from my own experience it if you have multiple environments and launch the build command without specifying which of them then it will build all of them.
To avoid this the -e option should be added like this:
Or you can set the default environment in your platformio.ini, which will instruct PlatformIO to only build the listed environments unless otherwise explicitly selected.
Since you are new to PlatformIO, now would probaly also be a good time to become familar with PlatformIO Home, and the built-in configuration editor, as it should make editing that platformio.ini a lot easier.
Thanks a lot for your explanation. I see that I still have to find my way with platformio (I have been using the Arduino-IDE for long, but did a project a year ago when I thought it would be appropriate for platformio).
I still got a question in this context here: if I would comment out the custom-table environment: would the build of the original environment still honor the modified partition table? It should have been changed once for all, right?