Oracle - Provide a more user-friendly way to update SCN

I currently use 1.6.1.Final, I have a few questions about 1.6.1.Final and 1.7.0:

1. Why does the *logMinerEventProcess#calculateNewStartScn method to get minStartScn not skip transactions without events?
2. MemoryLogMinerEventProcessor: Why does scn update only after all transactions are completed when support for LOB fields is not enabled? 
3. InfinispanLogMinerEventProcessor: Why update the SCN without any judgment when support for LOB fields is not enabled?(3.1 Is it because the createCache method will load the cache in Infinispan during initialization? 3.2 If so, why are there any judgments when enabling support for LOB fields?)
4. In both LogMinerEventProcessors, the calculateNewStartScn method may return minCacheScn as the new start scn. Will this not lead to repeated consumption of log events?