There are plenty of reasons why something you think should take a day might take a week. We often (fallaciously) assess a problem as "easy" without considering

There are plenty of reasons why something you think should take a day might take a week. We often (fallaciously) assess a problem as "easy" without considering the context in which it has to be incorporated, i.e. the codebase. The duration is moreoften a function of the complexity of the codebase, rather than the complexity of the isolated problem.