It shouldn't be too hard to figure out how many possible addresses there are that start witha prefix of a certain length. So it knows how big the key space is. And it can report what percentage if that space has been searched
The space is ~2^256 it will never search more than a very very tiny sliver of the space. Additionally there may, in fact, be _no_ solutions to your query (even a simple one like 1zzzzz*, though that is unlikely). Moreover, the search is randomized. Even if there were a solution, and even if you did evaluate ~2^256 points you may still have not found it (and in fact could search forever without finding it).It's not incorrect to show a longer expected time for a prefix of 12 than 4, of course. But what is incorrect is an indication that goes _down_. If it tells you it will take 1 hour to find an 8 character prefix, it should tell you that it expects 58 hours for 9 indeed. But if you've spent a half hour on your 8 character search and still not found one, it should still be reporting 1 hour. Not 30 minutes. Your probability of finding a solution is not appreciably increased by all the times you've failed to find one because the probability is independent (given cryptographic assumptions).
