So the 1914 doctrine is solid only in the minds of those who are also willing to mindlessly assume that Jesus was talking about an overlapping generation.
I suspect that not even 5% of active JWs could give you the scriptural explanation for how they arrive at 1914 (seven times, etc etc). At the very best, the average JW would explain the 1914 doctrine based on "the signs" that occurred -- war, famine, pestilence, etc.
And many couldn't explain it other than tell you to GO TO JW (dot) ORG.
The current batch of JWs do NOT know any doctrine.