Hello Görgen
First of all, there are two related timers with OSPF which should be clarified here. There’s the LSRefreshTime which is the timer you mentioned in your post which by default is 30 minutes. This is the timer that Rene mentions in the lesson, which is the interval at which OSPF will flood an LSA to ensure the LSDB stays up to date. The MaxAge is the maximum age an LSA can attain within the LSDB, which is 60 minutes. After this interval, the LSA will be purged from the LSDB. The MaxAge timer is reset every time an LSA is received. More about these can be seen in the following section of the OSPF RFC:
Now after doing a bit of research, I have found that on Cisco devices, you cannot change these values. Other vendors allow you to modify these, however, the benefits of doing so are few. There are other parameters that you can change to fulfill the needs of your OSPF topology. You can find quite a bit of information in this thread of the Cisco Community Forum:
I hope this has been helpful!
Laz