Experience from "MO" project. It much resembled the wise joke that "9 women don't bring 1 baby in 1 month".
Good outsourcer company I worked for was approached by very-huge-and-important-client (some international analytics agency). They wanted impressive solution to automate processing of various reports from 3-rd party companies they were "rating". The documents came in many different formats and overall task seemd extremely puzzling. However, client wanted solution quickly, say in 6 months. This outsourcer in turn was cool in that they never were afraid of short projects.
Thus about 150 specialists were allocated to work on the project (or rather set of subprojects) during the first month. It soon became a real mess: I myself was made a team-lead of the team which incorporated all people not assigned to more specific teams yet. Every daily standup I discovered some people left and some new people were added - and my team soon grew from 3 to about 20 members. Ironically we made certain progress during the first month, when we were few. But with explosive growth of the "population" work soon converted into numerous calls and heated debates about what should be done and how.
I left the company soon, but was informed by colleagues the project nevertheless was completed, though it took twice more time than expected and with overall feeling that the amount of work done was adequate for 20-30 people rather than 150. Still the client was less or more satisfied, so it was not a total failure.