Julius,
It has been a while since I worked there, but my recollection is that when in doubt, they locked it. Since the intention was to have a reporting instance with production data of <24 hours old so that long running reporting transactions would be run there so as to not slow down the regular production client, report transactions were not locked. It may sound like a flawed plan, but it seemed to work for that large SAP shop of 50K+ users.
Gretchen