VTP is not use in real life , at least in my experience. Major concern is Security and Vlan Management. Mostly it is due to luck of Security in VTP version 1, 2. VTP v3 came out with some security included so it may change real-world usage in feature.
Major thing about VTP transparent mode (real life and exam purpose) is the fact that is does save vlans in switch running config (and start up) but not in database.
You must use transparent mode to add Extended-range of VLANs 1006 to 4094. Again, those extended and normal range vlans are not added to the VLAN database but are saved in the switch running configuration.
VTP version 3 supports extended VLANs in server and transparent modes.
One thing about transparent mode used Real World is Private vlans. I have seen Private vlans in real world and if you travel and spend nights in hotels, you did too. Private vlans provide isolation and L2 security for medium-to-large number of vlans in area (building). You can create sub-domains within vlan domain and assign ports to it. it is great way to provide extra level of security as your individual access to Internet in your hotel room is separated from mine.
Here is snap of Cisco about transparent mode:
VTP transparent switches do not participate in VTP. A VTP transparent switch does not advertise its VLAN
configuration and does not synchronize its VLAN configuration based on received advertisements.
However, in VTP version 2 or version 3, transparent switches do forward VTP advertisements that they
receive from other switches through their trunk interfaces. You can create, modify, and delete VLANs on
a switch in VTP transparent mode.