As a highly experienced agency, often we know exactly how long a certain task will take.
At times, though, a task requires a certain amount of research and development to first find out what is needed (ex: finding what is causing an issue) before we can implement the solution.
We understand that at times this R&D time can take much longer than a simple task, and often much longer than the time needed to implement the solution.
Sometimes this time (and therefore cost) does not bring a positive ROI and you may decide it's not needed. If so, we understand. Otherwise we do our best to make sure to be as efficient as possible with this time as well as to give you a very broad and padded estimate to help ensure the R&D time does not extend past the original estimate.