Once this level of detail was generated, the next step was to get the senior engineering leads talking to the Product Manager and the designers to get some idea about the feature, look at some workflows and implementation, and then, start looking at how to estimate these. There are many methods of estimation, but in most cases we used the method called heuristics, which is a fancy word that we took to mean that these people knew how to do feature development, they had been doing it for quite some time, and as a result, they would be able to use their experience to determine the typical effort required for doing the feature.
Next, all the effort for the list of features was tabulated, and then assigned to the different members of the team while doing balancing, ensuring that everybody got a mix of interesting and boring work (wherever possible if there was exciting work, since that would help in terms of morale). There was some rationalization of the effort reported to take into account that some of the team members were more capable while others were not so capable. Finally the list of features would be generated to be presented to the stakeholders of the team and the organization.
However, once the team would start actually doing work on these features, then the actual effort would come into play. It was quite possible that the initial effort that was listed was the final effort once the team started implementation, but there was also a high chance that the effort would change once the team actually started implementation. There could be design issues that were not expected before actual implementation started, or there could be other setbacks that happened. It could be that the person doing the estimate had not done a correct estimate and this was clear when the team actually started the estimation.
This has an impact on risk planning. Part of the continuous effort to monitor the risk involved in the project is to determine the actual state of the project and also to determine whether the features that were expected to be done in the initial planning are on schedule or not. However, it should be part of the risk matrix to try and determine the level of inaccuracy present in these estimates (even though it can be pretty difficult) and to estimate the impact this could have on the feature schedule. It is critical that the Project / Program manager has been tracking the estimate accuracy of the features and is not majorly surprised if a feature is running late because of estimation issues.