#3 is not as a great as an idea as the other 2. Although many people still do it and it is fine for today. It is important to know that if you have half the seed, that does not mean that to guess the other half, the security budget is 50%. It is an exponential reduction in difficulty. The search space reduces from ~ 10^76 to ~10^36.
Whilst, with today’s compute it is still impossible to guess the remaining 12 words, the compute capability evolves rapidly over time.
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