The SYSTEM tablespace is just like any other data file (in this perspective, anyway). It needs to be monitored for I/O utilization and distributed appropriately. You should monitor I/O on your server over time and determine if one or more mount points are more busy thany the others. If so, dig into the file placement and try to spread your I/O load around to other devices.
Originally posted by kburrows
Also is system datafiles are treated like app data files then I should put them on the same disk as the app data files, right. It seems there would be lots of contention?
No, not necessarily. Just as I wouldn't put all my DATA data files on one disk, I wouldn't put my SYSTEM data files on one disk. You can initially set your system up as described, but monitor for I/O hotspots.