I am often confused about block time and numbers of actual shares >90% - I am still very new to this mining, but so far I understood that we all try to solve the actual block and if somebody else find we start over with a new one and even more with arrival of new transaction, they in included in calculation - so at all we again start over? How often? After every new transaction, after 10, after 100 or it`s limited? If we always start over - we at all ever try more then 1-5% of possibs on one calculation?