I have mentioned this in other threads, but feel it should be repeated.
Last seasons Halloween and Christmas I ran a master and 2 FPP/Pi Zero as remotes. The Pi Zeros run with no USB Storage. I use the a one drive system, using the Micro SD for storage as well as the op. So if anything can corrupt the boot system, this should. However, I did turn off all logging, so there were no writing to the SD.
Throughout both show I shut down every night, using power off via smart relays timers. The shutdown sequence was not used, I just cut the power 15 minutes after the FPP schedule ended.
In addition, with the abundance of rain in California this year, I experienced several ground fault shutdowns, while the show was running.
You would think with all the shutdowns, scheduled or not, I would have corrupted one of the boot systems, but not once. I think the key is to turn off all the logging......not likely going to change a read only system.