Please note that while we’ll always endeavour to make our estimates as accurate as we can, there is often unforeseen complexity and unknowns that make truly spot-on estimates nigh on impossible (if that wasn’t the case, a robot could do our job. Maybe one day....).
This is especially true as an app gets more complex. Each additional change has to take into account a wider range of touchpoints. Even a simple new search dropdown might warrant a database structure change, refactoring, bulk updating of existing data, and an hour or two of tests and bug fixing. All that is to say, we may occasionally get features which take less or longer than our estimate, but as mentioned , we’ll do our best to communicate this timely and adjust our planning accordingly.