The main part of Nessie not relying on the inside effects is because it's outside effects make up for it. You clearly have a visual of Nessie's cave before diving into it, whereas with Verbolten, the building is exposed before you hit the "tunnel" so the inside effects have to make up for that loss of realism.
With that being said, I agree with PR saying that Vbolt's effects will be around for a lot longer than Nessie's.
With that being said, I agree with PR saying that Vbolt's effects will be around for a lot longer than Nessie's.