I think there is no such standard. That depends on what technology u have. For example u can see TS use 7/8 without any problem. So it totally depends on operator.
why u people are crying like this..
See th 11590 tp. It is carrying 54 channels with 3/4 frq.so large number of channels will be accommodated in remaining dvbs2 tps, even though they are in 3/4